Injury aside, David Robertson due for decline

Helping save the planet may have never hurt the Yankees so much.

David Robertson said he felt better Friday after suffering a bone bruise on his right foot earlier this week taking a box out for recycling. But he was still in crutches and a walking boot and won't play catch until early next week.

Robertson solidified his spot in the Yankees bullpen -- and possibly as the team's future closer -- with an All-Star 2011 in which he posted a 1.08 ERA. But even if Robertson's 2012 preparations weren't interrupted by a freak injury, is there reason to think that repeating his stellar 2011 is a long shot?

Robertson's jaw-dropping 1.08 ERA was second among all MLB pitchers last season with a minimum of 50 innings pitched. His 2.8 WAR was tied with then-Chicago hurler Sean Marshall for third highest. Robertson's 13.50 K/9 was also third among relievers.

But there are some reasons to expect regression this season. We're not talking regression to the level of Robertson suddenly turning into the second coming of Buddy Groom; we're just talking about Robertson returning to the level of somewhat mortal pitchers.

For one thing, there's Robertson's walk rate. His 4.73 BB/9 was 12th highest among relievers with a minimum 50 innings pitched. Robertson is known for his Houdini-like escapes from pitching jams, but walking hitters at such a high rate increases his likelihood of getting into those jams in the first place.

Robertson has an unbelievably high 89.8 Left On Base percentage -- fourth highest for all pitchers in MLB (minimum 50 innings). The average for pitchers tends to fall between 70-72 percent. Robertson's LOB rate has steadily gone up throughout his career, but this season the jump was so dramatic, and out of line with the norm, that you have to expect that number to fall. He had a 65.3 percent rate in 2008, 75.4 percent in 2009 and 78.4 percent in 2010.

Robertson was also aided by giving up just 0.14 HR/9. But that's a tricky thing to do consistently when you pitch your home games in Yankee Stadium. Much like his LOB rate, Robertson's HR/9 have been trending in the right direction the last several years and then took a dramatic jump into "unsustainable territory." He had a 0.89 HR/9 in 2008, 0.82 in 2009 and 0.73 in 2010.

Also consider this: No other Yankee reliever with more than 10 innings pitched in 2011 had a lower HR/9 rate than 0.44, and that was Mariano Rivera. Here's the rest of the group: Boone Logan (0.86), Cory Wade (1.13), Joba Chamberlain (0.94), Hector Noesi (0.87), Rafael Soriano (0.92), Luis Ayala (0.80).

This is not to say that Robertson implodes in 2012, but people may need to temper their expectations. There's going to be a few more runners scoring, a few more bumps in the road than you saw in 2011. Check out these two 2012 projections: Bill James sees Robertson with a 2.83 ERA while ZIPS has him at 3.06.

Not so bad at all. But there's still one other system that might matter a bit more right now: MRI.

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