Team win projections are as much an art as a science. You can have the most accurate projection system for individual players in the world, but it will end up being useless at the team level, if you don’t have a good handle on playing time for those men. Injuries, too, can play havoc: the PECOTA prediction for the D-backs was off by nine wins, and the majority of that difference was likely the result of A.J. Pollock appearing in only a dozen games, and Zack Greinke throwing fewer innings than he had in any year since 2007.
That said, there is quite a lot of consistency between the overall win total predicted by Fangraphs and Baseball Prospectus for the 2017 Arizona Diamondbacks [There is a third set of team projections available, CAIRO - but the ‘team’ tab on that appears to work only in Excel, which I don’t have] Fangraphs currently has Arizona at 29.2 fWAR, which when tacked on to their replacement level standard of 47.7 wins, takes us to 76.9 wins for the season, with a run differential of -36. Baseball Prospectus has us at 79 wins, with a run differential of -22, so just a couple of wins more. They have Arizona at 26.8 WARP, again close to the same as Fangraphs.
But if you break these systems down to the individual positions, there are some spots where there is quite a lot of difference between the two. Let’s see what they have to say about each spot on the diamond. Obviously, we are also comparing two different metrics in fWAR and WARP, so bear that in mind.
Off the bat (hohoho) there is sharp dissent. Fangraphs shows a three-way split, with Chris Herrman getting about half the at-bats, and Chris Iannetta and Jeff Mathis splitting the rest. BP goes for Iannetta as the main man, and there’s also a clear difference on Hermann’s value overall. FG has him at +0.6, while BP rates him below replacement level, at -0.4.
We might as well buy line-up cards with Paul Goldschmidt’s name pre-printed on them. No shocks here, both sides expecting him to get 90% or more of the at-bats here [minor note: FG has been updated to include yesterday’s signing of Daniel Descalso, BP has not] BP values Goldschmidt higher, at 5.7 compared to 4.2 for FG, with anyone else at or near replacement level.
Brandon Drury is seen as getting about 280 PA in both systems. The main variant is the importance of Ketel Marte. FG has him as the main man (350 PA), while BP gives him only 136 PA: there, Chris Owings and Nick Ahmed represent the bulk of the difference. Neither have a great deal of confidence in Drury (0.4 by both), but BP rates Marte higher, at 0.8 compared to FG’s 0.3.
Another sharp difference. FG goes with Ahmed as the everyday shortstop for the D-backs, while BP gives about the same amount of playing time to Owings. The latter is seen by BP as fractionally below replacement level, while FG rates Ahmed as positive, but only marginally, coming in at a value 0.5.
There’s a good degree of consensus at the hot corner. Jake Lamb gets about 85% of the playing time in both systems, with Drury filling in most of the rest. FG has Lamb at 1.9, while BP is a little more bullish (sheepish?) at 2.4.
Both see Yasmany Tomas as the team’s everyday left-fielder, getting about two-thirds of playing time, though they also agree about him falling short of replacement level (FG -0.3, BP -0.1). The rest is a smörgåsbord, with Socrates Brito next in line, but Drury and Jeremy Hazelbaker are also mentioned in both places at seeing action there.
A.J. Pollock is seen as second only to Goldschmidt in terms of playing time, getting 85-90% of the plate appearances in center. The question is, how good will be be? FG is more optimistic, at 3.2, while BP has him at 2.7: if he can stay healthy, I would certainly be inclined to take the over on those figures.
Both sites agree this will belong to David Peralta for 80% of the time, but BP likes him considerably more, valuing him at 2.5 compared to FG’s 1.0. They have Tomas getting the remaining 20%, while Fangraphs splits it multiple ways, across Tomas, Brito, Hazelbaker and Oswaldo Arcia.
Below, find a table summarizing the projected playing time and value from, in columns 2 and 3, Baseball Prospectus, then in columns 4 and 5, Fangraphs.
BP vs. FG: 2017 Position Players
The easiest way to compare the two system here is probably to go straight to a chart: below, you’ll see both systems’ numbers for the predicted innings pitched, ERA and WARP/fWAR out of the 2017 Diamondbacks rotation.
BP vs. FG: 2017 D-backs rotation
The main difference between them, appears to be both the role and effectiveness of Patrick Corbin. BP has him as a starter, while FG sees him spending more time as a reliever - albeit tossing about an equal amount of innings in each role - and with an ERA close to half a run better. However, despite the better ERA, FG gives Corbin a lower overall value, of 0.8, compared to BP’s 1.2 - it seems the impact of him throwing 66 more innings, outweighs the superior performance. Of the rest, Robbie Ray looks to stand alongside Greinke at the top of our rotation, while Shelby Miller will... not suck? I guess I’d settle for that.
Let’s do the same for the projected bullpen, comparing the innings pitched, ERA and value of those pitchers.
BP vs. FG: 2017 D-backs bullpen
As you’d expect these numbers have rather more variation across the board in terms of playing time and performance - reliever volatility is a thing, folks. Fernando Rodney, Randall Delgado and Jake Barrett average out as the top three in terms of innings, which makes sense since they’re about the only “sure things” in terms of bullpen spots for 2017. Interesting to note that Fangraphs appears much more hopeful on just about every relief arm we have; that wasn’t the case for starters, so it may not be something systemic. 11 of the 12 bullpen pitchers to appear on both lists have a better ERA from them, and the 12th (Zack Godley) is just .01 higher there.
What does it all mean? On one level: absolutely nothing. These are just projections, and as such, have zero influence on what will happen between the lines for Arizona this season. But we all like to peer into the future and see if there is reason for hope or not. What both systems seem to agree - at least at this point - is that the D-backs pitching will probably not be as bad as it was last year, so there’s that. But how much, and to what extent this will play into any improvement in the team’s overall record, will only be decided in April, when the meaningful games start.