Within the next week -- Sept. 1, to be specific -- major league rosters will expand by two, which is bound to bring about more prospect call-ups.

Not 60, mind you. Most teams will choose to add a reliever in one of those spots, seeing as the pitcher maximum is also increasing from 13 to 14. Some will then use their second spot on a third catcher or a utility player, maybe someone who's just coming off the IL or has spent most of the year shuttling to and from Triple-A.

But there will be some prospects that we see for the first time, and as always, the first half of this article is dedicated to identifying those prospects, albeit with some caveats.

The term "prospect," you may have noticed, is rather broad. At its broadest, it refers to any player who hasn't exhausted his rookie eligibility yet, but people like to add their own qualifiers. A common one is that the player has to be highly regarded, showing up on all the rank lists and projecting for a significant role in the majors. That's never been a qualifier for this article, which sometimes even expands the definition of prospect to special cases like Noelvi Marte, but an idea inherent to the first half of the list, the Five on the Verge, is that the player has to be worth stashing ahead of time.

Some of the prospects likely to be promoted Sept. 1 are worth commenting on but not necessarily worth stashing. I'd like to highlight a couple of those here.

Let's name him for the last two structures I unlocked in SimCity! That's how I imagine Parks Harber, born in 2001, came to be, but the 24-year-old has worked hard to make sure that's not the most noteworthy detail about him. He has routinely put up good numbers as he's ascended the minor league ranks, first in the Yankees organization and now in the Giants. In 99 games between Double- and Triple-A this year, he's slashed .290/.376/.497, homering 17 times. The data doesn't jump out at you, but his exit velocity readings, both average and max, as well as his strikeout rate, walk rate, pull-air rate, chase rate and zone-contact rate are in the 50-70th percentile range, which is to say that none are prohibitive. The whole may be greater than the sum of the parts here, and because Harber plays third base, where the Giants have lost Matt Chapman for the rest of the season, now would be the perfect time to give him a whirl.

Michael Arroyo, meanwhile, actually does show up on some top 100 lists, but he doesn't have the loudest toolset for Fantasy, delivering modest exit velocities with an elevated chase rate at Triple-A. He's also been more good than great between the top two levels this year, slashing .281/.357/.459 with 17 home runs and 16 stolen bases in 105 games, and doesn't have as neat of a path as Harber. Sure, the Mariners have a need in their infield after losing Brendan Donovan and Colt Emerson to injuries, but Arroyo has played mostly left field of late and can only handle second base otherwise. Cole Young, the Mariners' usual second baseman, has played some shortstop in the majors, but he doesn't rate out well enough for them to trust him there full time.

I wouldn't rule out Harber or Arroyo making a Fantasy impact down the stretch, which is why I wanted to highlight them here, but I wouldn't be turning cartwheels if I heard either was coming up tomorrow. So which prospects would prompt that sort of response from me?

FIVE ON THE VERGE

(Here are the prospects most worth stashing in redraft leagues.)

Walker Jenkins, OF, Twins

2025 minors: .286 BA (308 AB), 10 HR, 17 SB, .850 OPS, 50 BB, 76 K
2026 minors: .323 BA (279 AB), 14 HR, 17 SB, .976 OPS, 43 BB, 50 K

Walker Jenkins is the one out of these five who I feel all but certain will be up, whether it's on Sept. 1 or even a little before. Not only do the Twins need him, fighting to stay in the playoff race while Byron Buxton contends with a balky hip, but he seems to have peaked at Triple-A. He's always had the mature approach and superlative hitter instincts, but the power has come through of late, with eight of his 14 home runs coming in August. He's also batting .411 (30 for 73) with seven stolen bases for the month. Even while being sidetracked by injuries throughout his minor league career, he's remarkably polished for a 21-year-old. The Twins couldn't justify leaving him in the holster after choosing to buy rather than sell at the trade deadline.

Ralphy Velazquez, 1B, Guardians

2025 minors: .265 BA (483 AB), 22 HR, .839 OPS, 52 BB, 104 K
2026 minors: .292 BA (414 AB), 27 HR, .936 OPS, 51 BB, 94 K

If you think Jenkins is hot, check out what Ralphy Velazquez is doing. With another home run Tuesday, he's up to 14 in August and 16 in his past 23 games. The Guardians are the team attempting to hold off the Twins (among others) for the third wild card spot in the AL, and they're most starved for offense, particularly with Jose Ramirez still struggling to regain his form following a fractured hamate bone. They did attempt to address their offensive needs by acquiring Jo Adell and Nathaniel Lowe at the deadline, but both are more like supporting characters than stalwarts. Lowe, who's directly blocking Velazquez, has been particularly quiet of late.

It's not even totally accurate to say Lowe is blocking Velazquez given that the Guardians don't have a dedicated DH. They've been rotating different players through there as a way to get Angel Genao in the lineup, but I wouldn't say that all three of Genao, Travis Bazzana and Brayan Rocchio need to be playing every day. Velazquez chases a little more than you'd like, but he doesn't strike out much for a player with his kind of power and is able to realize that power fully with a high pull-air rate. The Guardians may prefer not to rush the 21-year-old, but the opportunity to catch lightning in a bottle here may be too great for them to pass up.

Seaver King, SS, Nationals

2025 minors: .244 BA (505 AB), 6 HR, 30 SB, .631 OPS, 32 BB, 116 K
2026 minors: .323 BA (356 AB), 18 HR, 14 SB, .963 OPS, 44 BB, 86 K

A report from a couple weeks ago said the Nationals were unlikely to call up Seaver King this year, but the same report from Spencer Nusbaum of The Athletic acknowledged that the 23-year-old could force the issue. King's recent performance would seem to be doing exactly that. Over his past 15 games, he's batting .431 (28 for 65) with eight home runs and five stolen bases. His plate discipline is still suspect, but his exit velocity readings and expected stats are all in the 80th-90th percentile. And it just so happens that the Nationals are looking to shift their franchise shortstop, C.J. Abrams, to second base before the year is done, ostensibly to give Nasim Nunez a look at shortstop, but no matter what Nunez provides on defense or the base paths, it's pretty clear he's not the answer offensively. The Nationals may have nothing to play for, but if they view King as a Rookie of the Year candidate for next year, with possible draft pick rewards in play, it wouldn't hurt to let him get his feet wet now.

James Tibbs, OF, Dodgers

2025 minors: .243 BA (457 AB), 20 HR, 10 SB, .802 OPS, 90 BB, 120 K
2026 minors: .298 BA (447 AB), 27 HR, 7 SB, .974 OPS, 92 BB, 121 K

While I wouldn't go so far as to call James Tibbs a fixture in the Five on the Verge this season, like Kade Anderson was, his first appearance there came way back on April 8. It would be fair, then, to say we've been waiting all season for an opening to develop in the Dodgers outfield. Well, that opening finally came this weekend in the form of an injury, but wouldn't you know it was to their center fielder, Andy Pages, who's expected to miss basically the rest of the regular season with a fractured hand?

Tibbs can't play center field. Mike Sirota, another Dodgers outfield prospect, can, and I don't think we can rule out the possibility, however remote, of him arriving straight from Double-A. But for now, the Dodgers are opting for Diamondbacks castoff Alek Thomas, which deals a pretty big blow to their lineup. Tibbs has continued to light up the scoreboard at Triple-A, catching fire again recently with a .347 (25 for 69) batting average and six home runs in his past 20 games, and for as loaded as the Dodgers are, they could actually use some of that right now. Would devoting one of their extra roster spots to Tibbs, allowing him to split at-bats with a struggling Teoscar Hernandez, be so far-fetched? Not to me.

Lazaro Montes, OF, Mariners

2025 minors: .241 BA (490 AB), 32 HR, .858 OPS, 83 BB, 169 K
2026 minors: .248 BA (440 AB), 37 HR, .922 OPS, 74 BB, 162 K

I called Lazaro Montes the longest of long shots for a late-season promotion just two short weeks ago, but a lot can happen in two weeks. One thing that's happened is that Montes has quickly adjusted to Triple-A, having a huge August with a .289/.379/.663 slash line and nine home runs. The strikeout rate is still north of 30 percent, but if the Mariners are waiting for that to get better, they might just be waiting forever. Meanwhile, Montes' 94.3 mph average exit velocity and 116.3 mph max at Triple-A are akin to what Munetaka Murakami has delivered in the majors, and Murakami has made it work with an even higher strikeout rate.

High strikeout rates are potentially ruinous, but the way around them is to clock the ball in a manner that Montes is fully capable of. It's not the most cautious approach the Mariners could take with a 21-year-old who has a clear flaw remaining, but as they slip further back in the AL West, they may be willing to pull that lever. Where? Wherever. I for one, am not so sure Taylor Ward is working out in Seattle.

FIVE ON THE PERIPHERY

(Here are some other prospects doing something of note.)

Bo Davidson, OF, Giants

2025 minors: .281 BA (449 AB), 18 HR, 19 SB, .844 OPS, 68 BB, 119 K
2026 minors: .284 BA (422 AB), 25 HR, 19 SB, .870 OPS, 47 BB, 101 K

When I last featured Bo Davidson here in early July, he was blowing up at Double-A, bouncing back from a rocky start to the season. A promotion to Triple-A soon followed. Maybe he's just one of those prospects who needs some time to adjust to a new level because the same pattern has held there: several weeks of struggles before burning so brightly with a .463 (25 for 54) batting average and six home runs in his past 13 games that it invites talk of him being ready for the next move.

Well, the next move would be the majors, where he could get that difficult adjustment out of the way at the end of 2026, with nothing on the line, rather than waiting until 2027. I kind of doubt that's how the Giants play it -- Davidson hasn't even gotten 40 games at Triple-A, after all -- but this is one of those instances where the top of my Five on the Periphery serves as overflow for my Five on the Verge. Davidson delivers premium exit velocities and isn't so easily fooled at the plate, so if he could just elevate the ball to his pull side a little better, he'd be the complete package.

Jesus Baez, SS, Cardinals

2025 minors: .242 BA (388 AB), 14 HR, .713 OPS, 46 BB, 80 K
2026 minors: .270 BA (400 AB), 35 HR, .892 OPS, 25 BB, 70 K

For all the ink spilled over Joshua Baez's power this year, would you believe that another J. Baez in the Cardinals organization now has more minor league home runs than him? I'm referring, of course, to Jesus Baez, a 21-year-old shortstop at Double-A who homered three times Sunday and tacked on another Wednesday, giving him 35 on the year. He makes loud contact, hitting absolute screamers to his pull side, and has stopped squandering those hard hits on ground balls and pop-ups this year. He doesn't profile as much of an on-base threat and almost certainly won't stick at shortstop (third base is a possibility), but now that he's introduced himself as a slugger, Baez deserves to be mentioned among the top prospects.

Bryan Rincon, SS, Phillies

2025 minors: .181 BA (299 AB), 6 HR, 40 SB, .602 OPS, 50 BB, 103 K
2026 minors: .272 BA (379 AB), 21 HR, 26 SB, .914 OPS, 78 BB, 99 K

Bryan Rincon came into this year with a career .206 batting average in almost 800 minor league at-bats, so you'll excuse the rank lists for being slow to move him up. But he's clearly figured things out at the plate, standing out most for his plate discipline. He's reached base at a .405 clip, and Baseball America reports that he averages more than four pitches per plate appearance. He's also now a 20/20 man, and before you credit it all to the favorable hitting environment in Reading, note that his away splits are nearly identical to his home ones. Rincon's standout tool prior to this season was defense, and it's not like he's given anything up in that regard. He may be the most underappreciated prospect in the game right now.

Bryce Mayer, SP, Astros

2025 minors: 4-6, 4.11 ERA, 1.17 WHIP, 87 2/3 IP, 27 BB, 112 K
2026 minors: 5-3, 2.92 ERA, 1.13 WHIP, 83 1/3 IP, 38 BB, 112 K

Bryce Mayer is one of those Astros prospects who seems to pop up out of nowhere, and he really seems to have found his stride in his past eight starts, overcoming earlier control issues to put together a 1.83 ERA, 0.86 WHIP and 11.4 K/9 with a 16 percent swinging-strike rate and .178 batting average against. The key for him is a wipeout sweeper that Baseball Prospectus describes as "a nightmare for right-on-right batters when he keeps it glove-side and effective as a back-foot weapon against lefties as well."

Mayer's fastball is ordinary by modern standards, sitting in the low-to-mid 90s, but it plays up due to his low release and plus extension. Lesser pitchers with similar traits have worked out pretty well in the majors, and now that Mayer has reached Triple-A (three starts in), the 24-year-old is trending toward an early 2027 debut.

Yostin Pena, OF, Yankees

2026 minors: .366 BA (213 AB), 12 HR, 31 SB, 1.060 OPS, 27 BB, 38 K

For the purposes of this article, I generally avoid discussing players at the Rookie levels because they're so far away and facing such weak competition that it's hard to draw reliable conclusions. But Yostin Pena recently graduated to full-season ball, Low-A Tampa, and has already homered four times in his 16 games there. His exit velocities are so impressive that he's earning 70 power grades as an 18-year-old. A lot could go wrong for him still, but anyone who generates that kind of power at such a young age has a chance to be special. If he makes quick work of A-ball, reaching Double-A before his 19th birthday, his prospect stock will skyrocket.

Add CBS Sports on Google