The A’s: Taking Roster Construction to the Next Level

I started writing this post prior to the trade deadline; viewed through this lens, the Lester-and-Gomes-for-Cespedes trade makes even more sense for the A’s than it already did, especially considering their parallel acquisition of Sam Fuld from the Twins.

The A’s are ahead of the curve again.  This time it’s not just about better overall player evaluation (concentrating on certain metrics that other teams undervalue), but about building a roster that maximizes each player’s skill set to get the most out of the talent on your roster.  I wrote a while back that WAR is not the be-all, end-all of player evaluation, emphasizing that there is more to Wins than WAR.

WAR is great at certain things; it’s useful to remove factors that are outside a player’s immediate control: park factors, sequencing, etc.; it’s useful for comparing players across eras by controlling for run scoring environments and translating Runs to Wins; it’s also useful because it encompasses multiple aspects of a player’s skill set (hitting, defense, baserunning), and uses the same units (Runs and Wins) to combine these into a single number.  It’s a nice package.

But if I’m a GM, I don’t evaluate each player in a vacuum.  I want to know how he fits into my system, my lineup, my park, etc.  A given player will bring different value to different teams.  Some examples:

  • Certain players might be more tailored to certain parks based on their offensive profile.  A contact hitter who hits a lot of infield singles and steals a lot of bases isn’t worth as much (compared to a team playing in league-average conditions) to a team filled with roided-up sluggers playing in pre-humidor Coors field – the value of those stolen bases and infield singles just isn’t as high.  WAR does normalize for park factors, but it assumes all players are affected by a given park equally, which on its face isn’t true.
  • A player’s contribution varies based on how his team uses him.  If a team platoons a player so that he often has the advantage, his offensive contribution (per plate appearance) will be increased, whereas if he faces a more standard distribution of pitchers, his contribution would be lower.  Likewise if he plays a position he’s not as used to for the good of the team, his own contribution (as measured by WAR) will be less than if he plays his primary position.
  • Likewise, defensive versatility has value to a team.  A player who can play multiple positions allows his team more flexibility in roster construction and in-game management; setting the daily lineup, platooning, and late-game substitutions (matchups when pinch-hitting, or defensive replacements – especially double-switches in the NL).

As a GM, you don’t just add up each player’s projected WAR (and add in the replacement-level constant) and say that’s how many you project to win that year.  There are all kinds of interrelated variables at play that will determine how your team performs.

The A’s are the epitome of this philosophy and appear to be better at this optimization of roster construction.  They’ve loaded up on defensively versatile players with outsized platoon splits and are the king of the platoon.  They’ve started doing this in the last few years, and this year even more so.  Take a look at MLB averages for platoon splits as compared to the A’s:


Matchup PA OPS
vs RHP as RHB 45802 0.686
vs RHP as LHB 44345 0.719
vs LHP as RHB 22940 0.739
vs LHP as LHB 9951 0.651
With Platoon Advantage 67285 0.726
Without Advantage 55753 0.680


Matchup PA OPS
vs RHP as RHB 998 0.714
vs RHP as LHB 2021 0.755
vs LHP as RHB 925 0.751
vs LHP as LHB 260 0.584
With Platoon Advantage 2946 0.754
Without Advantage 1258 0.687

We notice two things: first, the A’s splits are a bit wider than the league splits: their righties hit better against lefties by about the same split as righties league-wide, but their lefties really hammer righties: a .171 OPS split for A’s lefties, as compared to a 0.068 split for lefties league-wide.  They’ve made a conscious effort to go after this style of player.  Second is the distribution of plate appearances: the average team gets 55% of its plate appearances with the platoon advantage.  The A’s get 70% of their plate appearances with the platoon advantage.  They’ve constructed their roster in such a way that they can alter their day-to-day lineup as much as possible to maximize the platoon advantage.

What allows the A’s to do this?  Defensive versatility (and the DH).  They’ve got guys like Brandon Moss playing LF/RF/1B/DH; Craig Gentry playing all OF spots; Stephen Vogt playing RF/C/1B; Alberto Callaspo, John Jaso, Josh Donaldson, and Bud Norris dividing time between DH/1B/3B/C; and so on.  All this versatility allows them to mix and match their lineup to get as many plate appearances with the platoon advantage as possible.  And, by not being pulled down by having any full-time DH, they get additional flexibility.

Cespedes didn’t really fit in with this philosophy.  Nearly all his appearances came in LF – 343 PAs, compared to 17 as a CF and 69 as a DH.  With the exception of Donaldson (423 PAs as 3B), he had the highest concentration of PAs at a single position.  The next-highest was Crisp, a switch-hitter, with 306 PAs as a CF.  Everyone else is playing all over the field.

Cespedes has a bit of a platoon split (0.844 OPS vs. 0.765), but not as much as other A’s like Reddick (0.843 vs. 0.398 this year), Donaldson (1.098 vs. 0.704), or Norris (1.031 vs. 0.771).  Gomes’ platoon split: 0.875 vs. 0.722.

So maybe the A’s think there isn’t that big a difference between Gomes and Cespedes, especially considering that Cespedes’ defense can be partially replaced by Fuld’s, his performance against lefties can be replaced by Gomes, and his performance against righties can be replaced by the left-handed Vogt, who stands to get more appearances in LF now.  If they play their cards right, Fuld/Gomes/Vogt is a better player than Cespedes.

The A’s appear to have a leg up on the competition.  Rather than evaluating players in a vacuum and estimating “How many wins we will get if we add player X and remove player Y?”, they’re looking at “What does our lineup look like with player X?”  “How will his presence affect the number of plate appearances players A, B, C, and D get (with platooning taken into account)?”  “How will our various defensive alignments look?”  “How does his presence affect the availability of late-game pinch-hit and defensive replacement options?”  And for each of those questions, they boil it down to the impact on expected runs, expected runs allowed, and expected wins.  They’re all-in for this year, and they’re pulling out all the stops to optimize their lineup.

Next up, I want to look at whether there are any signs of the A’s trying to get a similar edge based on:

  • Park factors – targeting players who fit in with their park
  • Clutch hitting ability; the A’s lead the league in the split between hitting with runners on base vs. with the bases empty; why?  Is it just luck, or have they found a way to get players who are better at hitting with runners on base?

Print This Post

Sort by:   newest | oldest | most voted

Good article on the limitations of strictly WAR for player evaluation. I think you mean Derek Norris though, instead of Bud


Wouldn’t you expect bullpens to take advantage of heavy platoons? And that Oakland would be forced to do more late game hitter substitutions?


The defensive versatility of the A’s bench helps to offset the opponent’s use of specialist RPs, since Melvin doesn’t necessarily have to wait for Norris to come to bat to pinch hit Jaso. Melvin can play the match-up and just shift the defense later around to make it work.

Additionally, there are really only three players (Donaldson, Crisp, and Lowrie) that play full-time. Donaldson is too good to platoon, and Crisp and Lowrie are both switch-hitters. Pretty much everyone else on the roster has an opposite-handed counterpart on the bench. Obviously, most of these guys are counterparts for multiple players.

Basically, it’s hard to force Melvin’s hand in the late innings because he’s very adept at manipulating his roster. If a team pushes the A’s into extra innings, however, Melvin has probably played all of his cards, and THEN a team can take advantage of the A’s heavy platoons (if they still have the arms in the bullpen to do so).

A Deicke
A Deicke

Another factor to be considered is that the A’s bench is more involved in playing day to day than players simply used as a defensive replacement or PH. For player morale and motivation, this involvement is large.


This was a really good read, thanks for posting it.

On the park factor note, if the A’s really are all-in for this year maybe you’ll find that Fuld and Gomes have good expected performance not only in O.Co, but also in Angel Stadium and Camden Yards. ;)