#### Chris Chrisman · @chrischrisman

13th Dec 2012 from Twitlonger

I was struck by the fact that, in 2011 and 2012, the Rockies and their visitors had identical wOBA at Coors Field (.346 and .372, respectively). The run production of the Rockies and their visitors, however, typically has been different. Looking back over the past several years, the Rockies have had it easier than their opponents in scoring runs, even when their team wOBA has been comparable to their opponents'. Good news for Rockies hitters.

That good news (maybe good fortune) didn't translate to Rockies pitchers last year, who surrendered a gobsmacking 523 runs at Coors Field in 2012. That's 96 more runs than the Rockies allowed at Coors Field in 2011 (427). The visitors' collective wOBA was higher, too, clocking in at .372 last season, 26 points higher than 2011.

If you assume a constant correlation between wOBA and runs scored, then a 96-run difference spread over a .026-wOBA difference is .000271 wOBA points per run. If you also assume that the Rockies have work to do in restoring their respectability, the answer lies less with improving the hitting at home and more with reducing the ghastly wOBA and runs put up by opponents at Coors Field last year. In fact, the goal should be returning to the 2011 benchmark, meaning a .026 reduction in wOBA to eliminate 96 opposition runs.

The target of 2011 -- .346 Opp wOBA -- isn't an idle one, if you believe that reducing Opp wOBA to that level would likely reduce runs allowed back to 427. If the 2013 Rockies offense scores 486 runs at home like they did in 2012, that would mean the Rockies would have the advantage of runs at Coors Field of 486-427 in 2013, a ratio of 1.14 to 1. That's very close to the ratio achieved by the Rockies at Coors Field in 2009 (1.16:1), although not as good as 2007 (1.20:1) or 2010 (1.26:1). But returning to 2009-levels of dominance at home would be terrific, since that Rockies team netted a 51-40 record at Coors Field. 51-40 means the Rockies could have a sub-.500 record on the road and still garner 90 wins.

The goal, then, is to reduce Opp wOBA by .026, no small feat. Where to start?

Fewer walks would help. Rockies pitchers walked a mind-numbing 269 batters at Coors Field last year. Amazingly, that's fewer than they walked at home in 2011 (276). Ignoring this inconvenient fact, and going back to 2010 levels, would be a big start to reducing baserunners and, by extension, runs. In 2010, Rockies pitchers walked only 232 at home. If the Rockies return to this number in 2013, then all other opposition statistics from 2012 being equal, they'd reduce Opp wOBA by 0.008. It's not close to our target of a .026 reduction, but it puts us well on our way. Of course, that assumes that walks become outs, not hits, which is dubious. But let's keep going.

Fewer home runs would be nice, too. Whether you blame the ballpark (like O'Dowd) or the lousy pitching (like me), the reality is that Rockies pitchers surrendered 118 home runs at Coors Field last year. That's way, way more than the Rockies' average of 83.6 per season between 2007-2011. It's even more than the 101 home runs given up in 2011. To reduce the Opp wOBA like we need to, though, the Rockies can't simply go back to the 101 given up in 2011. That would only reduce wOBA by .007, an acceptable reduction with respect to walks, but not with respect to the biggest contributor to wOBA. To restore their dominance at home in 2013, the Rockies need to reduce home runs back to the 2007-11 average: 84. Doing that would decrease Opp wOBA by 0.012. Added to the reduction resulting from fewer walks, that gets us to .020 lower Opp wOBA for 2013. Close, but not enough.

Reducing home runs doesn't get us as far, in part, because I assumed that every one of the 34 fewer home runs would be a single. That's possible, of course, but what if half of these (17) dropped harmlessly into the gloves of outfielders instead of resulted in base hits? That reduction in singles would reduce Opp wOBA another .004, to .024, and puts us within spitting distance of our target.

Tightening the defense would help get us there, in particular, by reducing the number of triples surrendered. Triples might be the most exciting play in baseball, but they're often attributable to poor defense as much as they are to poor pitches. The Rockies gave up 29 triples at Coors Field in 2012. That's one fewer than the 30 surrendered at home in 2009, but still above the average between 2007-11 (23.6). Returning to previous average -- 24 -- would take Opp wOBA down exactly .002 more points, to our target of .026.

The problem is that we should probably treat these 5 fewer triples as 5 additional doubles, not singles, and so that raises the difference to only .025. But if just two of those additional doubles become outs, then the 2013 Rockies can give up the same number of doubles that they did in 2012, and total Opp wOBA will still fall by .026. The Rockies' Opp wOBA for 2013 therefore would be .346, resulting in only 427 runs. If the Rockies offense puts up the same numbers as in 2012, that means outscoring opponents 486-427, hopefully capturing the same 51-40 home record as the 2009 team, which outpaced opponents at Coors Field at similar rate. Too damn bad we'll go 0-81 on the road.

Even if there are a ton of buried assumptions, it's an interesting mental exercise in showing how far the Rockies need to go to get back to good, and confirming the areas in which they need to improve. There's almost a Kiplingesque moral to it:

1. Throw strikes. Walks account for a not insignificant portion of the problem. Rockies pitchers need to throw 67 fewer over the course of the season. That's less than one a game, but it's not as easy as that. Those batters can't get on base another way, whether by a single or a kicked ball or a pitch into a ribcage. Fewer walks must translate into more outs. So when people say Rockies pitchers need to put the ball over the plate, that's true, but it's incomplete. Those need to be pitches that result in outs.

2. Don't give up the long ball. 118 home runs simply will not cut it. Neither will 101, the number surrendered in 2011. Saying it is one thing, though, and doing it is another. Again, a goodly portion of those home runs need to become outs, not extra base hits. The ideal is pitchers who miss bats entirely. If that's not in the cards, the best alternative is ground balls.

3. Play better defense. Keeping the ball in the park in general, and on the ground in particular, doesn't mean much if the defense stinks again in 2013. Some of that lousy defense is obvious (booted balls, errant throws), but some of it is more subtle, in the form of bad routes to fly balls or poor throws to cutoff men. Those subtle lapses turn doubles to triples and, eventually, into runs. The tide of poor defense, which has been flowing in for several seasons now, needs to be turned in 2013.

So there's my take on where the numbers show improvement needs to be made. A lot to do, and most can't be done in one year, if at all with the current crop of starting pitchers. But it's the season of miracles, so one can hope.