David Robertson Closing for the Yankees

With the injury to Mariano Rivera, the New York Yankees will be looking to David Robertson as well as Rafael Soriano to close games.

Robertson has been lights out this season. His strikeout rate leads the league at 46.7%, and his K/9 of 15.75 is third behind Jonny Venters' 17.42 and Jason Grilli's 16.36.

Robertson's chase rate is up from 25.0% in 2011 to 32.0% so far in 2012.  His heat maps indicate that he's been hitting the edge of the strike zone more.

It looks like Robertson has avoided throwing in to righties so far this season, while also peppering that outside edge to lefties. That kind of control near the zone means hitters are forced to protect more.  Borderline pitches are swung at more and this has lead to that big jump in his K-Rate.

Mariano Rivera Versus Lefties

Yankees' closer Mariano Rivera notched his 602nd career save yesterday, making him the all time saves leader.  And he did it much like the 601 that came before.  Rivera has been as close to a constant that the game of baseball has seen in the last two decades.

This year, Mariano Rivera has mostly been his usual dominant self, although he's had a few rough outings scattered throughout.  Looking at his splits, it seems like lefties, against which he is usually deadly, have hit him a bit better.

First, let's compare his pitch location from this season to the previous three:

Mariano Rivera (Click image to enlarge)

There isn't a tremendous difference, although you can see a bit more pitches out over the middle of the plate this season. 

Mariano Rivera Overall

	G	P	PA	AVG	BABIP	OBP	SLG	wOBA
2008-2010	209	3293	831	.181	.229	.222	.260	.213
2011	61	876	224	.217	.279	.247	.292	.237

The one thing that stands out is the jump in batting average on balls in play. It's always difficult to determine whether a BABIP jump is a result of decreased effectiveness or luck. For relievers, the sample size is fairly low for one season making it even more difficult to surmise.

However, we do know that it is mostly left-handed batters that account for the BABIP jump.

Mariano Rivera vs. LHB

	G	P	PA	AVG	BABIP	OBP	SLG	wOBA
2008-2010	195	1631	423	.181	.221	.226	.251	.212
2011	55	391	106	.238	.289	.267	.327	.261

Opposing left-handed batters have seen more than a 65 point jump in BABIP against Rivera this season. From 2008-2010, lefties had a 17.5% line drive rate. This season, it is up to 21.5%. This is hardly enough of a bump in such a small period of time to suggest Rivera is getting hit harder. So while it's possible more lefty batters have been squaring him up better, the increase in BABIP is probably more a product of luck than anything else. When coupled with the fact that his strikeout rate against LHB has been 21.7% this season, which is unchanged from his previous three year average, it is even more likely that we're not seeing an actual decline in effectiveness versus lefties.

Update on Tuesday, September 20, 2011 at 6:29PM by Bill Chuck

Here's 81 to know about the great Mo!

http://www.billy-ball.com/2011/09/the-great-mariano-rivera/

Soria Steps Down as Royals' Closer

Aaron Crow has replaced struggling Joakim Soria as the Kansas City Royals' closer.  Heading into Monday's game, opposing batters were hitting .288/.374/.463 against Soria.  He blew yet another save today (his second in two days) yielding 3 runs on 4 hits in the ninth inning versus the Los Angeles Angels.  The two-run HR he gave up to Torii Hunter was the 4th he's allowed this season which matches his 2010 total.

Right handed batters are a major source of Soria's troubles.  Through May 29th, they were hitting  .302/.388/.581 against him for a .412 wOBA.  In 2009 and 2010 combined, righties put up a measly .269 wOBA.  His location this season is likely a major reason why he's struggled against them.

(Click to enlarge)

Soria was pretty consistent at keeping the ball away from RHB over the last two years, getting beat mostly when throwing over the middle of the plate.  This season, he seems to be living in the middle, and is paying the price for it.  Specifically, Soria has been leaving his cutter middle-in to RHB.  From 2009-2010, righties mustered a .274 wOBA against his cutter.  This season, he's thrown 100 cutters to righties and his wOBA against on the pitch has risen 200 points to .474.

Getting his control over the cutter would go a long way towards helping Joakim Soria regain the closer's role in Kansas City.