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Where do projection systems disagree?

For most players, ZiPS and Steamer have the same opinion. But what happens when they butt heads?

Will Buxton's defense reach its elite potential in 2016? Answers vary.
Will Buxton's defense reach its elite potential in 2016? Answers vary.
Kim Klement-USA TODAY Sports

Disputes have always fascinated me. Whether they pertain to politics, weather or something even more trivial — like baseball — there's nothing, in my opinion, quite like a difference in opinion. For that reason, I've long enjoyed looking at the gaps between baseball projection systems. Last offseason, I ran a series entitled Mediating Projections, in which I looked at some of the more significant gaps between Steamer and ZiPS; I continued the series this offseason.

To wrap up the latter version, I thought I'd take a more objective look at these projections. Previously, I had selected the players arbitrarily, simply looking for differences that seemed large. Now, though, I've conclusively found the biggest gaps. According to the FanGraphs Depth Charts, 185 position players will accumulate 500 plate appearances this season, and 89 pitchers will surpass 160 innings*. Among these men, let's look for the largest fWAR disparities — denoted here as sWAR for Steamer and zWAR for ZiPS.

*Note: There won't actually be this many in either group, because injuries happen.

Let's begin with batters, whom we'll measure on a 600-plate appearance basis. Which ones have the largest differences in their ZiPS and Steamer projected fWARs for 2016?

Rank Name zPA zWAR zWAR/600 sPA sWAR sWAR/600 Diff
1 Byron Buxton 408 2.8 4.1 471 1.3 1.7 2.5
2 Justin Turner 345 2.6 4.5 491 2.2 2.7 1.8
3 Chris Carter 505 1.8 2.1 405 0.4 0.6 1.5
4 Odubel Herrera 567 2.5 2.6 622 1.2 1.2 1.5
5 J.D. Martinez 618 4.1 4.0 608 2.6 2.6 1.4

Buxton leads the list, and it's not even that close. ZiPS pegs him at a .311 wOBA, and Steamer projects a mark of .307, so offense doesn't cause this disagreement. The systems instead diverge when it comes to defense: The former thinks he'll save the Twins 13.0 runs, whereas the latter expects him to cost Minnesota 0.6 runs. Buxton's glove has an immaculate reputation — prospect analysts at both FanGraphs and Baseball Prospectus have given it a future grade of 70 — and if it can live up to that, his stardom will come sooner rather than later.

Turner and Carter each have multiple sources driving their gaps; I've covered both of them previously. Herrera debuted in 2015 with a 3.9-fWAR effort, on the back of two things: a .389 BABIP and 9.9 UZR. Staving off serious regression in both regards would help him fulfill ZiPS's projection, and a sophomore slump would prove Steamer correct. Through the past two seasons, Martinez has notched a monstrous .247 ISO, which ZiPS predicts will continue (.252 projection) and Steamer does not (.213 projection). Martinez' entire game revolves around power, so it is unsurprising the disagreement in projections does as well.

Now we'll look in the other direction. Which hitters receive more praise from Steamer?

Rank Name zPA zWAR zWAR/600 sPA sWAR sWAR/600 Diff
1 Adonis Garcia 402 0.0 0.0 459 0.9 1.2 -1.2
2 Marcell Ozuna 574 1.8 1.9 542 2.6 2.9 -1.0
3 Jayson Werth 438 0.4 0.5 443 1.1 1.5 -0.9
4 Mike Trout 688 8.5 7.4 647 9 8.3 -0.9
5 Yasiel Puig 569 3.3 3.5 572 4.2 4.4 -0.9

The gaps aren't as large in this direction, which has to do with the nature of the systems. Steamer takes a more conservative approach than ZiPS does — it is slightly more pessimistic on the best players and a little more optimistic on the worst ones. Since the players who get the most exposure tend to deserve it, this means ZiPS will generally think better of them. For these players, though, that doesn't apply.

Garcia came out of nowhere last year to smash a .336 wOBA in 198 plate appearances. That probably won't carry over to this season, but the extent of his decline doesn't look clear. Will he maintain some of the BABIP and post a .301 wOBA (Steamer), or will the cruel baseball gods claim his soul and reduce him to a .285 wOBA (ZiPS)? With guys like this, who don't have much of a track record to go on, we can't reach a strong conclusion either way.

Ozuna had a career year as 2014. Also, he has a much more distinguished prospect pedigree and is five years younger. At any rate, Ozuna possesses formidable raw power, which Steamer (.171 ISO) thinks he'll tap into to a greater extent than ZiPS (.158 ISO) does. The latter system also predicts a lot of strikeouts and middling defense, two of the things that sank him in 2015. The post-breakout trade candidate has potential, along with an overall uncertain future.

Werth and Puig each had down offensive years in 2015 as well, after top-notch production in the prior two campaigns. Despite their similarities, they have curiously opposing projections for 2015. Werth, a high-BABIP player before last season, has BABIP forecasts of .316 from Steamer and .282 from ZiPS; otherwise, the two systems line up. On the other hand, they give Puig identical BABIPs — and divergent strikeout rates, walk rates, and ISOs. Werth has less ground to make up to get back to where he was, but Puig has youth on his side, so neither one really has a sure shot at a rebound.

Then there's Trout, who is, well, Trout. With him, it's just a matter of how much he'll excel. Steamer has a bit more confidence in his baserunning and defense, and ZiPS foresees a higher strikeout rate and a lower BABIP. Regardless of what happens, however, he should remain the best player in the majors. This disagreement boils down to the distance between him and Bryce Harper.

With hitters out of the way, let's move to pitchers. ZiPS likes each of the following players more than Steamer does:

Rank Name zIP zWAR zWAR/200 sIP sWAR sWAR/200 Diff
1 Phil Hughes 167.0 3.2 3.8 198.0 2.0 2.0 1.8
2 Anthony DeSclafani 178.0 3.2 3.6 188.0 2.1 2.2 1.4
3 Justin Verlander 164.1 2.9 3.5 195.0 2.3 2.4 1.2
4 Kenta Maeda 177.0 3.6 4.1 172.0 2.6 3.0 1.0
5 Jeff Samardzija 196.0 3.7 3.8 195.0 2.7 2.8 1.0

Hughes is possibly the most captivating case of anyone in this article. ZiPS and Steamer project similar ERAs for him in 2016 — the former 4.10, the latter 4.20. They differ significantly when it comes to FIP, however: ZiPS foresees better strikeout, walk, and home run rates than Steamer does. Simultaneously, Steamer has a much more positive outlook regarding his BABIP and strand rate. It's a peculiar situation all around, and one that I may analyze more in-depth in the coming weeks.

With DeSclafani, much less complexity is behind the conflict. He has similar strikeout and walk projections from both systems; the discord stems almost entirely from home runs. Pitching in Great American Ballpark doesn't help his cause at all in that area, and overall there doesn't seem to be much reason for optimism. Likewise, long balls and punchouts explain most of the disparity for the last three men. Four-baggers can vacillate a lot for pitchers, so taking a definitive stance might not pay off. For Verlander and Samardzija, you have to hope that they've recaptured the strikeout magic and for Maeda, you have to hope that his talent will make the jump to MLB.

On the other end of the spectrum, let's look at the hurlers where Steamer takes the high ground:

Rank Name IP zWAR zWAR/200 sIP sWAR sWAR/200 Diff
1 Ian Kennedy 159.3 0.8 1.0 185.0 1.9 2.1 -1.0
2 Rich Hill 84.0 0.7 1.7 181.0 2.2 2.4 -0.8
3 Bud Norris 146.3 1.2 1.6 162.0 1.8 2.2 -0.6
4 Taijuan Walker 145.3 1.5 2.1 184.0 2.3 2.5 -0.4
5 Masahiro Tanaka 157.7 2.8 3.6 187.0 3.7 4.0 -0.4

Kennedy melted down last season (although he improved in the second half), and as with many of his teammates, home runs caused his troubles. Steamer expects Kauffman Stadium will aid him, whereas ZiPS thinks he's basically a lost cause. Norris, Kennedy's teammate for a portion of 2015, has a similar disagreement: He's moved to Turner Field, where the latter system projects more round-trippers than the former does.

Hill is weird. He started four games in 2015 and dominated enough to earn a $6 million deal (more than his career pay to date). At age 35, he won't stick around for long, but he could still be productive in the short term. If he can keep his walks down to a reasonable level, as Steamer prognosticates, he'll reward Oakland's $6 million gamble. Should he lose control again, he'll revert to his earlier, replacement-level self.

Walker and Tanaka each strike out a good amount of batters and limit bases on balls; ZiPS takes a more optimistic outlook in both regards. That system also thinks they'll allow a lot of home runs in 2016, as they did in 2015. Walker pitches in roomy Safeco Field, which gives him a better chance of fulfilling Steamer's projection, while Tanaka must work in the bandbox that is Yankee Stadium, making ZiPS the seemingly more realistic projection for him.

Of course, these are just a few of the cases. You can poke through all the players here. Whie ZiPS will usually take the over and Steamer the under, that rule has some exceptions.

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Ryan Romano is a contributing editor for Beyond the Box Score. He also writes about the Orioles on Camden Depot (and on Camden Chat that one time), and about the Brewers on BP Milwaukee.