On September 7, Brett Gardner was activated from the disabled list, after spending nearly a month and a half there. Since then, Gardner has appeared in a majority of games, but it is evident Girardi views Melky Cabrera as the Yankees' starting center fielder.
Now, there are very few ways to quantify the influence a manager has. One sure thing a manager can do to help his team is to have his best options on the field more frequently than lesser options. Is Melky Cabrera the Yankees' best option in center field, with Gardner on the bench?
On the season, Melky Cabrera has a line of .280/.342/.427 in 492 plate appearances for a wOBA of .337(the average is .329). After Melky's 2008 struggles, these numbers are a welcome surprise and have surpassed what most expected from him. Going forward, ZiPS predicts Melky will produce a line of .265/.321/.367 for a below average wOBA of .311.
While no one will tell you that these projection systems are perfect, they tend to be very reliable for players with extensive MLB experience. Melky is young and still has room to improve, but he is not a rookie with limited time in the majors. He has 2100 plate appearances in the major leagues, so chances are that the projection is pretty accurate.
Even when Brett Gardner won the center field job in spring training, expectations were not very high for him. Along with Melky, Gardner has transcended even the most optimistic projections. He has produced a line of .276/.350/.401 for a wOBA of .343 in 248 plate appearances. He has been slightly better offensively than Melky, albeit in a smaller sample size. ZiPS projects Gardner to regress to a .250/.325/.333 line from here on out.
If these projections held true, Cabrera would be worth around five more runs on offense than Gardner over the course of 500 at-bats. However, I see some real improvements in Gardner's offense this season. He is only striking out in 15.7 percent of at bats. He hasn't had a strikeout rate that low since his 2007 stint in AA. He has usually been over 20 percent. The reason for this is that Gardner swings at a minuscule 17.1 percent of pitches that are outside of the strike zone, while the league average is 25.1 percent.
I think that Gardner's projection is a bit pessimistic, but I generally trust that these systems know more than I do. As the projection system says, it remains to be seen whether Gardner can keep up this level of hitting. The only way to find out is to give him more plate appearances.
There are a few different systems I use to assess defensive skills. I find that using a few different assessments can paint a more accurate picture than using just one. If they all agree, then I am confident in their accuracy.
Tom Tango conducts a survey which results in his Fan's Scouting Report. For this season and last season, this report suggests that both players are above average fielders, which Gardner being a notch above Melky. Melky's arm strength is really the only place where he has an edge, but it is so large that it brings him close to Gardner.
Baseball Prospectus has defensive runs above average. For the season, it rates Gardner as being worth +8 runs and Melky as a +3 run center fielder. Remember, Gardner has had significantly less playing time than Melky as well.
Then, there is UZR, which is probably the best defensive metric available. UZR loves Brett Gardner to the tune of a career 26.0 UZR/150. It is a small sample size, but definitely agrees with the other assessments that Gardner is well above average. Melky, on the other hand, gets his worst rating from UZR. It pegs Cabrera as an average center fielder this season, and a below average fielder for his career, with a -6.0 UZR/150.
All three systems agree that Gardner is the better fielder, but they disagree on how big the difference is. Given this evidence, I'd say that Gardner would be 5-15 runs better than Cabrera over the course of a season in center field.
I don't think anyone can really argue this point. Gardner is one of the fastest players in baseball, and Cabrera has basically average speed. Gardner has stolen 34 bases and has only been caught six times. Melky has stolen 44 bases(over a much longer time period), and has been caught 14 times.
According to Baseball Prospectus, Gardner has been worth around 3.21 runs above average on the bases, good for 23rd in baseball*. This is a counting stat, and all of the players above him have had more playing time.
*Michael Bourn is first on the list, and he has been worth 15 runs above average, just in base running. Chris Getz is second on the list, and he's only been worth six runs above average. Bourn has been worth 1.5 wins on the bases, that is just ridiculous. Count me among the people who thought the Astros got ripped off in the Lidge trade, but Bourn has been extremely valuable this season.
Melky Cabrera has been worth just .38 runs on the bases this season, essentially average. Cabrera is a slightly above average base runner himself, but he still cannot match up to the speedy Brett Gardner.
After running through multiple aspects of their games, it is very evident to me that Gardner should be starting over Melky, and Girardi will only hurt the team if he continues to send Melky out to center field on a daily basis. This analysis is all based on Gardner's projection, and I think he is significantly more likely to outhit his projection than Melky is.
An argument that I've heard is that Gardner is more valuable off the bench than Melky, because of his speed. This is a weak argument; it is very easy to find a player who can run fast. It's not easy to find a player with Gardner's speed who also plays great defense and has good on-base skills.
The Yankees have suggested that they'd be open to having Freddy Guzman on the postseason roster. If they realize that Gardner is the superior option in center field, would Guzman be more valuable to the Yankees in the postseason due to his impressive speed? There is no doubt that Melky is the better player, but that doesn't mean he would be a better pick for the playoff roster.
In the first two rounds, I think a pinch runner offers a bit more value than Melky, who isn't a superior hitter to anyone who will be playing. At first, I thought the idea was absurd, but I am now warming up to the idea of Gardner as the starting center fielder in rounds one and two of the playoffs, with Guzman on the bench, and Melky watching from home.