You probably don’t need much of an introduction to Kyle Schwarber. His story has been told numerous times, and he gained legendary status through his late-season return from ACL surgery, hitting .412 in the World Series to help the Cubs end their 108-year World Series drought. Schwarber is probably one of the most well known young players in baseball.

Depending on how frequently you read FanGraphs, you may be aware of Aaron Altherr. Jeff wrote about him in March when he was having a strong spring, trying to earn more time than his slotted 4th outfielder job on the Phillies would give him, and I wrote about his breakout performance last week. But while Altherr has gotten some notice for his strong performance the last few weeks, he’s still a relatively obscure young outfielder.

But despite their significantly different levels of recognition, they may be more similar than their reputations would suggest. So today, I wanted to do something of a thought experiment, and gauge how our readership sees the pair, as of May 16th, 2017.

Both were rookies in 2015, putting up strong debut seasons in a little less than half-a-season’s worth of playing time. Both got hurt and had lost years in 2016. Both are currently starting in left field for their respective clubs this year, though Altherr began the year as a reserve, and is only now starting to play everyday after forcing his way into the line-up.

Let’s start by just looking at their career Major League numbers to this point.

Altherr and Schwarber, Career to Date Name PA BB% K% ISO BABIP Aaron Altherr 492 11% 28% 0.198 0.309 Kyle Schwarber 438 14% 28% 0.211 0.264 Name AVG OBP SLG wOBA wRC+ Aaron Altherr 0.238 0.338 0.436 0.336 109 Kyle Schwarber 0.219 0.338 0.430 0.336 110

To this point, everything is pretty similar. Both have shown patient approaches and contact issues that lead to both high walk and high strikeout totals, offsetting the latter with enough power to remain above-average hitters. Schwarber has shown a bit more power, while Altherr has run higher BABIPs, as he’s a right-hander who isn’t as easily shiftable as the left-handed Schwarber. Altherr also hits the ball at a lower launch angle than Schwarber, so he hits fewer high fly balls that are likely to be caught, which helps his BABIP but somewhat limits his upside ISO.

There are also a couple of factors not represented in these career lines, one for each that could reasonably argue that both players are better than these numbers suggest.

Altherr returned from a wrirst injury in 2016, playing poorly after getting back on the field, and it’s pretty easy to conclude that he wasn’t fully healthy last year, and that 227 of his career 492 PAs came while he was playing at less than 100%. While it’s not wise to throw those numbers out entirely, the lack of power he showed during that stretch can likely be somewhat explained as a result of his wrist issues. If he had stayed on the DL for the entire year, as Schwarber did while recovering from his knee injury, his career numbers would likely look even better.

For Schwarber, the numbers are his regular season totals, but when evaluating a player’s overall abilities, there’s no real reason to ignore his postseason performances. Those are not only the highest leverage at-bats a player gets in any year, but they also come against higher quality competition, and Schwarber has dominated in his two postseason runs, hitting .364/.451/.727 in 51 playoff PAs. If those had simply happened in the regular season, and thus were counted in his career line, he’d have a 121 wRC+ in 489 PAs instead of the 110 wRC+ in 438 PAs that are shown above.

So, both guys have had pretty strong offensive performances in the first part of their careers. Neither player has reached even a full season’s worth of playing time, so it’s not as easy to say that they are what their numbers say. And once you start to look back at their pre-MLB performances, Schwarber gains a pretty big edge.

Schwarber was the 4th overall pick in the 2014 draft, and destroyed minor league pitching on his way up the ladder. The lowest wRC+ he posted at any level was 166. He got to the big leagues after just about 600 minor league plate appearances, as the lower levels of professional baseball posed no real challenge to him.

Altherr was a 9th round pick in the 2009 draft, then had to repeat rookie ball after not hitting very well as an 18-year-old. He showed decent contact skills but minimal power in his first few years at the lowest levels, but then got dominated in 2011 when he was first exposed to full-season competition, putting up a 52 wRC+ in 163 PAs after getting to A-ball. He spent all of 2012 as a 21-year-old in low-A ball and still wasn’t great, putting up a 98 wRC+ in a league where he wasn’t young for the level.

He finally added some power in high-A in 2013, but then he put up an 87 wRC+ in his first exposure to Double-A as a 23-year-old. He cut his strikeout rate and increased his power in 2015, which got him from Double-A through Triple-A and to the Majors, but that was the first year in his minor league career in which he really hit at a high level.

So, from a longer-term view, there’s far more evidence that Schwarber can hit than that Altherr can. Schwarber’s hit against every level of competition he’s faced for years, while Altherr struggled until an age-24 breakout. Schwarber’s track record of offensive excellence is long and consistent; Altherr’s is very short and incongruous.

That’s where the case for Schwarber becomes pretty easy. The Major League numbers are only similar if you ignore what Schwarber has done in the playoffs, against high-quality pitching in games that matter the most, and his offensive strengths are supported by years of data, against every level of pitching he’s faced. Despite his early slump in 2017, we can be pretty confident that Kyle Schwarber is a good Major League hitter. There is far more uncertainty around that question with Altherr.

But that doesn’t mean Altherr doesn’t have a case himself. After all, the Majors are littered with good athletes who took a long time to get their swings straightened out, and became very different players after they figured out how to hit than they were before. And while we’ve only looked at career numbers so far, 2017 performance leans heavily in Altherr’s favor, as he’s put up a 194 wRC+ in comparison to Schwarber’s 78 wRC+ this year. The Statcast data supports the idea of him having legitimate power, and his plate discipline numbers and contact numbers are either similar or better than Schwarber’s across the board.

And, of course, we’ve only talked about offense so far. Schwarber is a 1B/DH playing left field because it’s where the Cubs can best hide his glove; Altherr appears to be a strong defensive outfielder who could play center if need be, and looks to be above average in either corner. While we only have 1,000 innings of data on Altherr and a little more than 500 on Schwarber in the OF, all the data points to the same conclusion; Altherr looks like an above-average defender, while Schwarber is probably below average.

Their career Statcast catch probability data, which should require the least amount of data to become somewhat informative, is below.

Statcast Catch Probabilities Player 5 Star 4 Star 3 Star 2 Star 1 Star Aaron Altherr 0% 30% 88% 82% 98% Kyle Schwarber 0% 25% 40% 75% 92% SOURCE: Baseball Savant

Catch probability is effectively just a speed metric, as a guy who positions himself better won’t have as many difficult plays to make, but it supports the idea that Altherr can cover more ground than Schwarber in the outfield.

Is the defensive difference enough to make up for the offensive gap? I don’t know! It depends on how big the offensive gap is, which depends a bit on how much weight you put on 2017 data, or at least, how little weight you put on Altherr’s lousy 2016 performance. And then, there’s the question of how heavily you factor in long-term track record, which clearly favors Schwarber. The projections that still see Altherr as a slightly below-average hitter remember that he didn’t hit very well in the minor leagues, and are factoring that into their forecasts.

But it’s interesting to me that we can even have this discussion, given how insane this would have sounded like a few months ago. Over the winter, Schwarber was an untradeable core piece on the best team in baseball, while Altherr was a fourth outfielder on one of the worst teams in the league, a franchise not actively trying to win in the short-term. Preferring Altherr to Schwarber would have sounded insane as recently as March. It’s now mid-May. Do we think things could really have changed enough in six weeks to make an insane-sounding comparison actually true?

I’m interested in hearing what you guys think. Has Schwarber’s slow start this year done anything to diminish your view of his potential? Has Altherr’s outstanding first 100 plate appearances of 2017 caused you to see him as a star in the making, or is that just small sample size overreaction?

To see what you guys think, I’ll end with a series of polls. I’ll combine the results, along with my brief conclusion, up in an InstaGraphs post tomorrow.