It hasn't gone the way we had hoped for these seven players so far. Whether due to injury, poor performance, or just plain bad luck, they've all underwhelmed to some degree. Some have managed to remain quite effective in spite of it — you can't be too mad at J.D. Martinez's season so far — while others have just been flat out busts to date — what's up, Jack Flaherty?

However, what all seven have in common is this: They're about to carry you in the second half. If you've got them on your team, sit tight; if you don't, go throw out some trade offers. There's big upside on this list, and you'll want them on your side when it's all said and done. 

Second-Half
Breakouts
NYM N.Y. Mets • #28 • Age: 37
Stats
AVG
.304
R
52
HR
18
RBI
48
SB
1
This one should be obvious, so I don't have to spend too much time on it, I think. Martinez has established himself as one of the game's premier bats, and while his .304/.376/.541 line is still very good, it's not what you were hoping for from a first-round bat without speed. And there are some signs that Martinez has slipped, as his barrel rate has dipped from 16.0% to 12.4% in 2019, while his average exit velocity is down from 93.0 mph to 91.7. Of course, his 2019 exit velocity is actually higher than 2017, his big breakout season, so that's hardly reason to be concerned. Per BaseballSavant.com's expected stat metrics, Martinez's batted ball profile should have led to a .416 wOBA, while he has just a .383 mark so far. Even if he doesn't improve his skills, better days are ahead for Martinez. Buy low now, if you can.
PHI Philadelphia • #10 • Age: 33
Stats
AVG
.273
R
55
HR
10
RBI
42
SB
4
Another player who has managed to be both very good, and more than a little disappointing, Fantasy players must be worried they bought into an unsustainable career year from Realmuto. On the contrary, he's been as good as we've ever seen him, with a career-high 90.4 mph average exit velocity and 42.3% hard-hit rate. With the exception of an elevated strikeout rate, Realmuto's underlying skill set looks as good or better than it ever has. The potential for that huge season you were hoping for is still there.
CLE Cleveland • #66 • Age: 33
Stats
AVG
.253
R
40
HR
20
RBI
51
SB
13
It may be a bit too late to buy low on Puig, who has continued his trend of starting off ice-cold before becoming an absolute terror. Puig was hitting below .200 as late as May 4 and had a .630 OPS for the season as recently as June 10; in 23 games since, he's hitting .390/.440/.805, with just a 14.3% strikeout rate. There are some Fantasy players who have sworn off Puig due to his inconsistency, but with the recent improvements in his strikeout rate, I expect Puig to continue to tear the cover off the ball in the second half. He's already on pace for around 35 homers and 25 stolen bases, and he'll be even better moving forward.
LAD L.A. Dodgers • Age: 29
Stats
W
4
ERA
4.64
WHIP
1.227
K
107
Progress isn't always linear, and Flaherty is 2019's poster boy for that. Widely expected to take another step forward after 2018's breakout, Flaherty has instead taken a step back nearly across the board, with his strikeout rate and groundball rate especially both moving in the wrong direction. This isn't an instance where you can just point at his peripherals and say with confidence that Flaherty will be better, as a 4.11 SIERA suggests he largely deserves his outcomes so far. No, in this case, you're betting on the skill set turning around. Flaherty's breaking balls have been the biggest issue so far, as he has allowed eight homers on his slider and curveball already, the same number he surrendered all of last season. He's not getting nearly as many swings and misses on his curveball as well, though the slider is still plenty good there. The hope is Flaherty could be just a few mechanical tweaks away from figuring it out, and the upside is high enough that you should try to snag him from a disappointed manager if you can.
PHI Philadelphia • #45 • Age: 34
Stats
W
6
ERA
4.69
WHIP
1.277
K
130
Maybe last year was the outlier for Wheeler, who has sandwiched his 3.31 ERA around seasons of 5.21 and 4.69. I was skeptical of Wheeler coming in for exactly that reason, but I'm at the point where Wheeler is exactly the kind of pitcher I want to target right now. His strikeout rate is up and his walk rate is down, and while his home run rate has normalized, I think he's likely to see better outcomes with runners on base than his current 65.9% strand rate suggests. Wheeler isn't the ace or near-ace some wanted him to be before this season, but don't let that disappointment overstate things; most of his peripherals suggest an ERA closer to 3.50 than 4.50. Bet on better days.
WAS Washington • Age: 29
Stats
AVG
.253
R
38
HR
25
RBI
42
SB
0
The common refrain when you hype Reyes is that he isn't consistent, but you know what … I don't care. He's a stud, and I'll live with the occasional cold spell, as long as the Padres actually stick with him. He has elite batted-ball metrics, and profiles as more of a .275 hitter than his current .253 mark suggests. He's started 12 of the Padres' last 13 games, as the Padres have largely abandoned the idea of playing Wil Myers every day. If Hunter Renfroe and Reyes keep hitting, that should remain the case, and the Padres still seem likely to pluck from their outfield depth to bolster the pitching staff before the deadline. Hopefully, that means locking Reyes into an everday role — in San Diego, or elsewhere. Either way, he's someone I want on my side.
TEX Texas • #44 • Age: 33
Stats
W
1
ERA
5.18
WHIP
1.248
K
49
Yeah, he's got a 5.17 ERA. It's ugly. I know. And it hasn't really been a result of bad luck, as Heaney just hasn't done a good enough job locating his sinker, leading to a 25-degree average launch angle (from 15 degrees in 2018) and a .378 wOBA allowed. It would be one thing if Heaney was getting more whiffs with the pitch by pitching up in the zone, but that hasn't happened; he's just getting rocked. Heaney has shown good enough command in the past that I think you can safely assume he'll sort that issue out, and with his curveball and changeup working better than ever as swing-and-miss pitches, the strikeout rate might be here to stay. If he can sustain the strikeout gains while keeping the ball on the ground more often, there's big potential here in the second half.