Righthanded hitting slugging outfielder Brian Barton had a big day Sunday, ripping as many home runs in a single spring game as he had in 82 major-league games in 2008 — two. It was a reminder that the former Rule-5 pick, who hit both dingers off lefties (Andrew Miller and Aaron Thompson), could make the team as an important righthanded platoon player.

If we assume that Rick Ankiel, Colby Rasmus and Ryan Ludwick break north as the starting outfield, that would leave room for possibly two other outfielders. Depending on how you consider Skip Schumaker and Joe Mather, both of whom can play outfield, the Cardinals may choose to keep only one additional outfielder. For this argument, we’ll assume that is contest is between lefty Chris Duncan and righty Barton. Given that the team’s outfield crew, Mather excepted, is lefty-swinging, Barton’s opportunity then lies in his ability to peform as a platoon player against lefthanders. How much would Barton be able to contribute, and is it worth taking Duncan’s spot? He’s not going to help with his glove, though neither is Duncan.

First, it’s worth knowing how many times the team will need a righthanded-hitting platoon player. That is, how many times do the Cardinals face a lefthanded starting pitcher? In recent years, the Cardinals have faced a southpaw starter in about a third of their total games (56 in 2008, 56 in 2007, 57 in 2006). In 2008, the team averaged 2.8 plate appearances per lineup spot per game against starters. That comes to about 156 plate appearances against lefthanded starters for any starting player.

If Barton plays in all of those instead of a lefthanded player, how much advantage does that give the team? Let’s do the math, backing up a bit to figure out a reasonable platoon split based on his 2009 projections, what percentage of PAs he saw vs. lefties and his career handedness splits. In 2008, Barton faced lefties in 60% of his plate appearances. He’s demonstrated a platoon advantage in 1606 minor-league PAs and 179 major-league PAs:

So based on his minor- and major-league numbers, we’ll make a rough guess and say that he exhibits about a three percent platoon advantage against southpaws; that is, he is three percent better vs. lefties than against righties.

Moving along, if we average four of the major projection systems, we find that Barton may provide a wOBA of .338 and around 1.0 weighted Runs Above Average:

If we use that 3% platoon differential and weight it for 60% of his PAs, that means that Barton will have around a .342 wOBA vs. lefties (.332 vs. righties) in 2009.

Then that brings us to Duncan, for whom we’ll do the same exercise:

Assuming a roughly 40% platoon advantage for Duncan, that comes to a projected .367 wOBA vs. righties (.262 vs. lefties) for 2009. Again, that’s assuming he has 82% of his plate appearances against righties and 18% against lefties.

But what if each of the players played exclusively against pitchers against whom he has a platoon advantage? Let’s break down each player’s Runs Above Average by platoon split. Again, we’ll assume that the Cardinals will face a lefthanded starting pitcher in 56 games, leaving 106 against righties. That comes to 156 and 295 plate appearances, respectively, against those starting pitchers only. The below chart shows how many wRAA each player would provide against each pitcher type:

If Barton played the entire season — against righties and lefties both — he would produce about 1.7 wRAA; not great. But if Duncan played every game regardless of pitcher, he would be even worse, with -0.1 wRAA. But if TLR were to keep both on the roster and play them exclusively against pitchers against whom they have a platoon advantage, the team could realize 10.7 wRAA — Barton’s 1.5 vs. LHP over 56 games plus Duncan’s 9.2 vs. RHP over 106 games. That would put LF as the team’s third-most productive position, behind 1B (Pujols) and RF (Ludwick).

The fact remains that the Cardinal outfield will likely need all hands on deck, anyway, so it may be a moot point. After all, Ludwick and Ankiel, the two biggest cogs, are injury-prone and are unlikely to each play 150 games. Barton and Duncan both will see action. Assuming that TLR plays them in the right situations, that can be to the Cardinals’ big benefit.

This entry was posted by Pip on Tuesday, March 3rd, 2009 at 10:02 pm and is filed under analysis. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.