If you play in a dynasty league, you know all trades must be made with great care. A wrong decision now could change the course of your team for years to come.
So generally, it's wise to reserve judgment when a player is doing something vastly out of the ordinary. That's true for any format, of course, but the stakes are much lower when you can fall back on "better luck next year."
By now, though, I'm willing to assume a degree of permanence for these changes and would be open to making bold moves considering.
In case you missed the dynasty update for the quarter-way point in the season, you can find it here. Now for how things stand midway through 2019 ...
Players who have gained the most value in dynasty
Ketel Marte, 2B/SS/OF, Diamondbacks
Marte was billed as more of an Ender Inciarte type coming up through the Mariners system, and even those who noticed his power increase over the final four months of last season couldn't have imagined he'd be on a near 40-homer pace midway through 2019. He may well be the top second baseman in Fantasy now, particularly with Jose Altuve continuing to flounder, and if you need another reminder of just how far he's come, allow me to point out that I passed him over for Andrelton Simmons late in my Tout Wars draft this spring. Sweet.
Lucas Giolito, SP, White Sox
Lucas Giolito has stumbled a bit recently, but my conviction here comes with a recognition that his breakthrough goes beyond just the numbers. His stuff is genuinely better this year — the fastball harder and the slider and changeup more effective — which has him nestled among the elite in terms of swinging strike rate. It shouldn't be so surprising given his former status as the game's top pitching prospect, but boy did his career begin poorly — to the point he could have been one of the biggest dynasty fallers at this time a year ago.
Brandon Woodruff, SP/RP, Brewers
A former minor-league strikeout leader (2016), Woodruff was always thought to have upside, but the fact the Brewers, a team whose biggest need over the past couple years has been pitching, couldn't find a rotation spot for him until his age-26 season had many a Fantasy player jumping ship well beforehand. Not only has Woodruff been dominant the past two months — particularly with regard to his fastball, a genuine bat-misser that sits around 97 mph and touches triple-digits — but also efficient, rarely logging 100 pitches despite regularly throwing seven-plus innings. After facing him, Bryce Harper said Woodruff resembled an early-on Matt Harvey, and the comparison seems apt.
Rafael Devers, 3B, Red Sox
After he failed to live up to the considerable hype last year, believers in Devers could only point to his elite pedigree as reason for hope this year, which might have been concerning if not for the fact player development often works that way. Simply because he debuted at such a young age, Devers saw his stock fall in dynasty leagues, and in retrospect, we should all be ashamed of ourselves for doubting a hitter once billed as the next Adrian Beltre just because he didn't deliver on it at age 21.
Max Kepler, OF, Twins
Kepler was a contact-over-power guy, sort of like Nick Markakis, when he first broke into the league and could have carved out a fine career for himself that way. But he didn't want to get left behind in an era when everybody who's anybody hits home runs and, to that end, made changes to his swing to elevate the ball more last year. Sort of like Josh Bell, though, it took a year for him to get comfortable enough with the changes to see an effect, and as with Bell, the Statcast data mostly supports the production.
Prospects who have gained the most value in dynasty
Cristian Pache, OF, Braves
Double-A: .297 BA (290 AB), 11 HR, 6 3B, 21 2B, .878 OPS, 25 BB, 71 K
Prospect publications that tend to emphasize skills over results already rated Pache fairly high, trusting that his athleticism so evident on the defensive end would eventually translate to the dish. It seems to be happening now — and in a way that's reminiscent of Ronald Acuna. By that, I mean it's applied across the board, his jump in power over the past month coinciding with a drop in strikeout rate and accelerating the 20-year-old's path to the majors.
Grayson Rodriguez, SP, Orioles
A-: 7-2, 2.18 ERA, 0.89 WHIP, 62 IP, 16 BB, 84 K
Though obviously still a long way from the majors, Rodriguez has distinguished himself from other projectable teenage arms by overpowering hitters with an impressive fastball-curveball combo. He's still learning to maximize his 6-foot-5 frame in terms of getting better extension and making more efficient use of his lower half, but if he's already this dominant this early in his development, it's an encouraging indicator of what his ceiling might be.
Deivi Garcia, SP, Yankees
A+/AA: 4-5, 3.01 ERA, 1.21 WHIP, 68 2/3 IP, 33 BB, 114 K
Any discussion of Garcia has to begin with his minor league-leading 14.9 K/9, which he owes both to his high-rpm curveball and his conviction to using it to its full effect. He recently had a two-start stretch in which he allowed one hit and recorded 24 strikeouts, so the biggest concern for him now might be if his 5-foot-9 frame will allow him to start over the long haul.
Isan Diaz, 2B, Marlins
Triple-A: .295 BA (281 AB), 18 HR, .951 OPS, 32 BB, 69 K
Though considered a prospect of some note when he went from Brewers to the Diamondbacks in a Jean Segura trade a few years back, Diaz had lost much of his luster by the time the Brewers tossed him in the Christian Yelich deal. Clearly, though, he's tapping into that forgotten potential now, and while you might attribute the power boost to the new baseballs being used at Triple-A, the improved contact rate is the bigger development for what now looks to be the Marlins second baseman of the (very near) future.
Logan Gilbert, SP, Mariners
A-/A+: 5-2, 1.97 ERA, 0.95 WHIP, 73 IP, 15 BB, 94 K
A bout with mono last summer kept the Mariners' first-round pick from debuting until this year, but Gilbert is off and running now, propelled by a lively fastball, plus control and two developing breaking balls. He's a bit like Trevor Bauer in that he constantly strives to improve himself through better understanding biomechanics, technology and data — a trait that prompted Mariners pitching coordinator Max Weiner to tell The Athletic, "You would be a fool to bet against him."
Players who have lost the most value in dynasty
Jose Ramirez, 3B, Indians
Maybe it goes without saying Ramirez's dynasty value has fallen, as bad as he's been in 2019, but it's still a stunning turn of events for a 26-year-old who was on a steep upward trajectory for four years prior to this one, culminating last year with him being in the running for best player in Fantasy. He was on the short list of players you'd want to build your dynasty team around, a five-category stud whose low strikeout rate gave him an especially high floor, and now ... what is he, just a steals specialist? Probably not, but much of the research out there suggests significant changes are needed for Ramirez to be even two-thirds of the player he was..
Bryce Harper, OF, Phillies
It feels like I should know better than to downgrade a player who went from being one of the most hyped prospects ever to an MVP of historic proportions, especially while he's still in his prime at age 26, but the fact is Harper has had only a half season, the injury-plagued 2017, with anything close to MVP-level production since that epic 2015. And by now, the skills erosion is evident. His strikeout rate has risen for a second straight year, to the point it would be difficult for him to be much more than the .250 hitter he is, so while he's certainly still valuable, he's a far cry from Mike Trout-level.
Paul Goldschmidt, 1B, Cardinals
He recovered from it last June, but we're into July now. And as he nears his 32nd birthday, it certainly looks like Goldschmidt is more oldschmidt than coldschmidt. It's not any one thing but a combination of him not hitting the ball as often or as hard or as much in the air, which have altogether led to an xBA and xwOBA that suggest he has only slightly underperformed. It's not unthinkable he still rebounds, but he's getting passed over by too many first basemen in an era of massive offense. Why bet on the old guy?
Miles Mikolas, SP, Cardinals
Mikolas was an atypical ace last year, succeeding in all the ways we should know better than to trust but are too desperate not to. Yes, if he could have sustained elite walk and ground-ball rates, he might have been able to overcome a poor strikeout rate again in an era when most contact tends to be destructive. But we're seeing now it was a big ask, as only the walk rate has held up. Mikolas is still useful in this capacity, but the lack of strikeouts is more of an issue when he profiles for a low-fours ERA rather than low-threes.
Yusei Kikuchi, SP, Mariners
Ranking the latest free agent signing out of Japan, who's technically a rookie, amid all the well-vetted prospects who dynasty owners know so well is an impossible task that usually ends with people like me sticking him somewhere in the middle hoping for the best. It gives the impression he's to be treated like a prospect, deserving of patience and perspective. But it's somebody Kikuchi's age (28), it's more a sink-or-swim proposition. And this one has sunk like a rock, offering virtually no redeeming qualities through 18 starts.