Nats in Town, Mock Gets Second Shot at Cubs

Garrett Mock got his first start of 2009 against the Cubs. That July outing lasted less than four innings. Since then, he's been better, but not spectacular, and has stuck in the Washington rotation.

Mock will face the Cubs and the freshly re-activated Carlos Zambrano. The Cubs have played well at home, but nothing is for certain with the 2009 North Siders.

Mock made a few relief appearances early in the season, was sent down and recalled for the July 19 game. After that brief thrashing, his ERA stood at 7.71. It's down to 5.10, but he's only completed six innings twice in seven starts since his call-up. His last three starts have seen his highest strikeout totals, and both of those "long" outings.

Mock made some starts in 2008. Tracking his pitch selections for non-relief appearances, there seems to be a slight trend since last season.



Lately, less sinkers and curveballs, more fastballs and change-ups. Oh, right, about his stuff...

pitch	#	MPH	PFX_X	PFX_Z	DEG	RPM
Change-up	182	81	-6	3	246	1310
Curveball	187	77	8	-8	44	1874
Sinker	473	92	-7	5	236	1823
Fastball	453	92	-2	9	192	1852
Cutter	6	91	2	6	164	1234
Slider	210	82	5	-1	77	1027

Not sure of those are real cutters, or just strange fastballs/data errors. I'm pretty much ignoring them, just a half-dozen anyway.

Mock has a couple good ways to induce a ground ball, neither being the sinker. The sinker also seems prone to yield line drives.



I like that change-up, good grounder and pop-up rates but little in between says "not easy to square-up". It also sports a .443 whiff rate. OK, I can see why Mock may be throwing it more.

It is his best pitch, using run values. Compared to the average pitch, Mock's change-up saves about two runs per 100 times thrown. That's based on either linear weights from batted ball outcomes (singles, outs etc) - rv100 - or based on distributed batted ball outcomes derived by batted ball type (liner, fly etc.) - rv100E.



Well, the sinker is no peach, so I can see why he's ditching it. Clearly, he's using linear weights (cough). He may be a little unlucky with it, and not a lot of pitchers manage a sinker that's on the good (negative) side of zero.

The two spots where rv100 and rv100E disagree most are on the fastball and the slider. If you think of the slider for right-handed opponents as you'd think of his change-up against lefties. rv100E likes both pitches, but rv100 is lukewarm on the slider. And sliders usually tally a negative (good) rv100.

As far as Mock's fastball is concerned, we're looking at another gap of about two runs per 100 pitches. rv100 hates the heater, rv100E thinks it's OK. It seems rv100E is forgiving his elevated HR/FB rate, by design, and liking his good line drive rate. Combined, it takes the sting out of the fastball's .708 SLGCON.

The difference in the slider is harder to explain/rationalize. Both measures use the same values for non-batted balls, and he hasn't allowed any home runs against it. His batted ball profile against the slider is fairly mundane (37% GB, 14% LD, 34% FB, 14% PU). Maybe he really has been unlucky on balls in play off the slider.

The SLGCON against Mock's slider is .600, which isn't horrific. It is higher than average by about .070. Sliders should be harder to hit than an average pitch, too. It's whiff rate is .361, about average for breaking stuff.

So, his fastball may be sub-par and his slider average. The change-up seems very good, anyway I look at it. And the sinker and curveball aren't good pieces to have, even if they haven't gotten the job done or fallen out of favor.