In the early going it can be tough to separate small sample size outcomes from real change. It’s even more difficult to tackle the idea of regression, both positively and negatively, if you’re unsure of how to measure the uncertainty around the inputs. We’ll take a look at a few of the underachievers and overachievers and see what we can see.

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Negative Regression

Bryce Harper (OF – WAS)

I need to get this on the record before I start. Bryce Harper is really, really good at hitting baseballs really, really hard. Okay? I get that. However, to this point in his career, he’s been almost exclusively a pull-field power hitter. Yet to open this year, he’s looking a lot more like J.D. Martinez or Giancarlo Stanton in the air. Hey, he’s 25 and a perennial MVP candidate so everything he’s done is theoretically sustainable, but I have a feeling you’ll see the SLG and ISO come back down . . . unless they don’t and he replicates his age-22 2015 season with the .330/.460/.649 triple-slash with the 41 HRs. Of course, that season was also fueled by his lowest GB%, most flyball pull-field skewed and highest HR/FB% statistics on record. Just to give you a visualization to go with the numbers, I’ll show you Mr. Harper with Stanton and JDM as comps.

Gregory Polanco (OF – PIT)

I guess it’s hard to be a negative regresser when you’re batting .220/.330 for the AVG/OBP portion of your triple-slash, but it’s the .600 SLG or .380 ISO you should be skeptical of. Polanco is known for having an ~50/55 grade on his game power which translates to that 18-25 HR range, and I don’t see that having changed to open the year. He has barreled a few extra balls in the small sample size, but his average exit velocity on air-balls hasn’t changed. There has also been talk of him possibly having changed his batted ball profile or launch angles, but I don’t see much evidence to suggest that’s true either. You could use his hot start in the power department to cash-in on a power upgrade in a trade and feel good about it as he comes back to normal. As for the .220 batting average, that’s being held back by a .077 BABIP on ground balls. That’s one place you can expect Polanco to rebound.

Mike Moustakas (3B – KC)

Moustakas is doing exactly what you’d think he’d do, replicating his 2017 batted ball profile to a ‘T” in the early going. In case you were wondering if there was something new going on with his swing, there isn’t and his .327 AVG and .350 OBP is set to come crashing back to earth shortly. A theme among some of the negative regression subjects is BABIP on ground balls and Moustakas is the king, running a .600 BABIP in the early going. Don’t move your expectations from that .250/.310/.500 triple-slash line.

Matt Davidson (3B – CHW)

Mr. Opening Day! Matt’s strikeout problem has persisted even if he’s walked a little more frequently to start the year. Taking a flier on him after the big first few days to see if he could truly cut down on the K-rate this year and put more balls in play was a great idea, but now we’re in the midst of watching his 50% HR/FB rate come back down to earth while watching the Ks pile up. Davidson still looks like the same all-or-nothing slugger we’ve seen in past years, and I’d expect a White Sox lineup shake-up pretty soon with both Moncada struggling in the leadoff spot and Davidson in the clean-up role.

Tim Anderson (SS – CHW)

Before we hit the negative regression topics with Mr. Anderson, it’s worth noting that he’s been a more patient version of himself to start the season taking four walks in the early going. He walked only 13 times in a mostly full season last year. However, he’s also running a .500 BABIP to the pull side on ground balls to start the season against a career average of ~ .250. By way of comparison, someone like Jose Altuve, who also flies out of the box from the right side and hits the ball hard on the ground, has a career BABIP on pull-side grounders of .325. Anderson also has an early season HR/FB spike that’s above his true talent level. While I still believe Anderson is a 20/20 threat I wouldn’t get too carried away with the early success on the bases and through the air.

Francisco Cervelli (C – PIT)

Cervelli, a reported “launch angle change” guy, really is not. Sure, he’s hitting a bunch of poppers, which has moved his launch angle from 6° to 20°. However, that’s not why he’s currently slugging .535 with a .256 ISO. Those additional pop-ups that have raised his launch angle have contributed .000 to his wOBA. What is true is that he’s barreled almost everything he’s hit to centerfield and he has pulled the ball in the air more. The former being the source of his ISO spike and the latter being a positive trait to keep an eye on for the 32-year-old backstop.

Luke Weaver (SP – STL)

Everyone who doesn’t have a share of Luke Weaver is excited to see Luke Weaver’s name here. No, he’s not going to maintain his Kershawian-pace the entire season. He’s only a 45% groundball guy so he’s going to be subject to some home runs at some point during the season, though I do believe he’s shown a skill to suppress home runs in the minor leagues. So while he’s looking at a 2.02 ERA/2.72 FIP/3.63 xFIP line to open the season, I’d expect him to be an xFIP beater based on his minor league track record. Remember that xFIP regresses your home run rate to league average which likely isn’t an accurate description of Weaver. So you might be asking yourself, where is the negative regression? Oh yes, well that’s in the BABIP he’s running at a .250 rate right now. That’s driven by an .053/.053/.211 triple-slash on fly balls, which make up 55% of all his balls in play. So not only is he not giving up homers, but everything that’s being hit in the air is falling into outfielders gloves instead of in front of the outfielders or in the gaps. His career average on flyballs has been .256/.256/.911 with an 18.4% HR/FB ratio. On a positive note, he’s maintained his excellent ability to limit walks (7.5%).

Trevor Bauer (SP – CLE)

Bauer’s GB% is down to start the year and similar to Luke Weaver, his BABIP is being kept artificially low by fly ball luck to the tune of .130/.130/.217 against a three year average of .270/.270/.794. This includes the fact that his HR/FB% is currently sitting at 5.4%, probably thanks to all that cold weather in Cleveland to start the year. While Bauer has made strides with his K/9 and K-BB% due to stabilizing his walk rate, he’s likely not going to be an xFIP beater and you should expect some of those runs to pour in as the weather warms up and more fly balls start dropping in. This isn’t to take anything away from Bauer who is still likely to be a breakout pitcher in 2018.

Tyson Ross (SP – SD)

Just the appearance of Ross’ name on this list may be a surprise to some. Ross is back again with the Padres, where he last pitched a full season for them in 2015. The fastball velocity is greatly dimished, despite the fact that measurements for velocity skewed readings upward by a 1 mph or so last year with the new Statcast measurement point. So rather than throwing 94 mph, Ross has been in the 90 mph range when not working out of the bullpen since his return last year. Perhaps the Padres could benefit from shifting him to the pen at some point and letting him rear back and let it rip. For now, Ross’ 7.0 K/9 and 2.0 BB/9 both show his new approach. More control and fewer strikeouts. In his first incarnation with the Padres, he was more of a strikeout-per-inning guy while walking over three batters per nine. I don’t know if I’m buying the newfound control and with his lack of strikeouts I suspect he’ll start to take more of a beating as we get deeper into the season.

Positive Regression

Ryan Zimmerman (1B – WAS)

Despite hitting .136/.224/.250 to open the season, Zimmerman is still hitting the ball really hard no matter if it’s in the air, on the ground or somewhere in between. Luck seems to be against him as a majority of his well struck air-balls have gone to centerfield and have turned into outs. As we move through April into May you’ll start to see Zimmerman pull the ball more and these hard hit outs will begin to be hard hit wOBA-positive outcomes. The only thing to worry about with Zimmerman is that he seems to lose a game per week to Matt Adams, so his overall counting stats may take a slight hit this year.

Jeimer Candelario (3B – DET)

Jemeir seems to be getting dropped everywhere in shallower mixed leagues after his slow start, but I do think he’ll have the opportunity to heat back up with a long leash in Detroit and a cushy line-up slot. Currently batting .200/.290/.364 he quite literally has nowhere to go but up while hitting in front of Miguel Cabrera and Nick Castellanos. He has a good eye at the plate and an ability to put a lot of balls in play even if his major league strikeout rate currently stands at 23.9%. Based on his minor league track record I’d expect Candelario to bring his strikeout rate down to and perhaps below 20% as he continues to walk in approximately 9% of his plate appearances. While the trade to Detroit late last year may dampen his overall HR power prospects, the 24-year-old has shown a penchant for pulling the ball in the air, which can only help his game power numbers. I still think there are 15 HRs in his bat this year and he should hit .280-.300 the rest of the way.

Whit Merrifield (2B – KC)

If you have the opportunity to buy low on Whit Merrifield this April, please do. His slow start will give owners pause while they consider if he was actually for real last year. He was for real. He’s maintained the same batted ball profile to start the year, with the exception that he hasn’t hit the ball very hard in the air and the balls he has hit hard haven’t fallen. It’s not shocking given all the cold weather games he suffered through in DET and CLE to start the year.

Addison Russell (SS – CHC)

Addison Russell is walking more, striking out less and hitting balls at better launch angles in 2018 but the results just haven’t followed. The two biggest issues I can see are the large amount of soft contact he’s making along with trying to hit the ball back up the middle and to the opposite field rather than pulling the ball which is where all his power is through the air. Though I’ve never been a huge fan of Russell I do think his current performance on pulled fly balls and the mix of where he’s hitting the ball are skewing the overall reality of his skillset. The real bright spot is the ~16% K rate which would be a huge improvement and more in line with his minor league numbers which could signal he’s ready to take a step forward.

Ian Happ (OF – CHC)

Much like Russell, Happ has been unable to generate any exit velocity on his air-balls to start the season – he’s averaging 84.8mph this year vs. 92.1mph last year. While he’s still striking out a ton, he’s also putting a lot of balls in play in the air which would normally be a good thing for him and eventually will be again. This kid has power to all fields, remember hit hit 12/7/5 HRs to the Pull/Center/Opposite fields last year and once he gets rolling you’ll be glad he’s not on your bench. I will note that the only downside here is that while he struggles the Cubs do have the option to play the ageless Ben Zobrist and the equally talented youngster Albert Almora Jr.

Chris Taylor (OF – LAD)

Chris Taylor, who is currently triple-slashing .214/.237/.375, isn’t doing anything wrong to start the year other than not squaring up quite as many balls in this small sample as he did last year. Much like Whit Merrifield, if you know anyone who is selling you’ll want to be buying. Pre-season I described Chris Taylor as being a Lorenzo Cain clone and I still believe this to be true. Let the slow start doubt creep into someone else’s head and pounce on Taylor while his value is low. Conversely, if you already own him, I wouldn’t take him out of your lineup at all this year. Set it and forget it with Taylor.

Alex Wood (SP – LAD)

Alex Wood hasn’t walked a batter yet this season – that’s headline number one. Headline number two? His fastball velocity is down to ~88-89mph. Since it’s April and dead arm is a common thing, I’m willing to suspend disbelief on the fastball velocity and see if we get a course correction on the THIRTY-ONE POINT EIGHT PERCENT strand rate. Yes, that’s what we call unlucky. It’s not even due to an inflated BABIP (.241) or a HR/FB% spike (6.3%). It just really seems that Alex Wood has been the unluckiest pitcher in baseball through this point in April. Did I mention his groundball rate is higher than his career rate (56%)?

Lance McCullers Jr. (SP – HOU)

Poor Lance McCullers has started the year with a 40% HR/FB ratio to go with his 7.73 ERA /3.78 FIP/ 2.46 xFIP . Though the walks have been extremely troublesome and have inflated his ERA in combination with the early HR/FB spike, we’d still expect an ERA under 4. Regressing the home run rate back to league average, which is what xFIP does, shows a sub-3 ERA. Lance just needs to corral the free passes and let the defense use his 60%+ GB rate to turn grounders into outs at a better rate.

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Jim Melichar is a correspondent at FantasyPros. For more from Jim, check out his archive and follow him @JimMelichar7.