If you look at the Fangraphs leaderboard for wOBA and sort by ascending numbers you see a lot of prominent (or formerly prominent) names near the bottom of the qualified leaderboard. Carlos Gomez and Justin Upton have been the two worst-performing outfielders by wOBA with enough at-bats this year. Jason Heyward and Yasiel Puig rank 10th and 11th, respectively, or, in this case, un-respectively from the bottom. Elsewhere in the bottom 20 are Randal Grichuk, Corey Dickerson, J.D. Martinez and Alex Gordon. Below, I’ll dig into the stats and see which players should bounce back and which players you should stay away from.

Let’s start right at the top, er, bottom with Gomez. His .215 wOBA is 26 points lower than any other qualified outfielder, and only one outfielder with more plate appearances (Billy Burns, three) has fewer RBI than Gomez’s five. Gomez is striking out at a career-worst 35 percent clip, which is third-worst in all of baseball. His contact and swinging strike rates are also career-worsts; almost one out of every five swings he ends up hitting nothing but air. It’s not like pitchers are only taking advantage of Gomez’s swing-and-miss approach. He’s barely hitting anything IN the zone. Gomez’s late swoon in 2015 was blamed due to injuries, but so far this year there seems to be no claim of injuries. Gomez barely made it to double-digits in home runs last year, and with less to work with this year I don’t see any reason to expect a bounce back this year.

Upton‘s 38.8 strikeout percentage is far and away the worst in the Majors. If you look at Upton’s exit velocity numbers he’s been above-average for three straight weeks, and he’s crushing pitches in the zone but has an average above .273 in only two of nine sections of the strike zone. Upton’s strikeouts have always been high, but I’m willing to bet on the 28-year-old getting going soon. He’s been too good before, in much worse lineups and/or stadiums to think that he’s suddenly done.

On this date last year Heyward was hitting .236 with a .631 OPS. Today, he’s hitting .236 with a .624 OPS. Heyward isn’t hitting for any power, but he’s getting on base at a .347 clip thanks to a stellar 13 percent walk rate. I know the goose egg in the home run column is frustrating/worrisome, but he’s averaged fewer than 13 a year for the past three seasons. There’s a very good chance he could hit that many the rest of the way. Heyward is on pace for another 20-steal season, and the Cubs aren’t afraid to run so he should get there easily. Pitchers are attacking Heyward low in the zone, and he’s hitting poorly on those pitches, according to Baseball Savant. However, he’s swinging at a career-low rate out of the strike zone as well as whiffing at the second-best rate of his career. He might not be a source for power (I think he’ll turn it up soon), but in this lineup he should be productive for the rest of the season.

Puig had eight hits in the first four games of the season, but since then he’s hitting .202/.234/.311 with seven strikeouts for every one walk. Jeff Sullivan explored Puig’s struggles here. Tl;dr: He can’t hit the inside fastball and swings way too much low and outside. He says Puig has made an adjustment before similar to what he’ll have to do to get out of this one, so it’s believable to say he’ll rebound soon. But to what extent? The Puig of 2013 isn’t coming back, and last year his .181 Isolated power mark was equal to Brandon Moss and his 19 home runs. Puig is super-talented, but his full-season high in home runs is 16. Even if he does start hitting better I don’t know that his ceiling is that high.

Martinez is hitting .230 with a .697 OPS. One year ago he was hitting .244 with a .779 OPS. It’s still early enough that one good day will up his rate stats to an equal level. In fact, after a home run today his OPS is .731. He’s on pace for around 25-30 home runs, and he’s got improving strikeout and walk rates to go with mostly normal power numbers. I’m buying where I can.