I wrote about defense yesterday and while commenting to myself, I mused about double plays and the Mariners ability to turn them. Jeff recently winked at the subject as well, crafting a Valentine to Brendan Ryan's part in the whole affair. It caught hold of my brain because my way of measuring team defense, which involves calculating how well they turn batted balls into outs compared to the league at large, after correcting for distribution of type (e.g. ground ball) and park (parks have an effect!) doesn't include double plays.
I don't, or haven't yet, given defenses extra credit for creating extra outs. I've been ignoring double plays. Not intentionally mind you, it just hadn't crossed my mind to my memory. It did now so I pondered for a bit and then came up with this formula.
The number of double plays turned divided by the number of opportunities to turn one, for Team compared to the MLB not including Team.
It's a straightforward idea I think. A rate stat is preferred because defenses will not all face the same number of chances to execute a double play. Counting stats are almost always less preferable to rates, with counting stats being useful mainly to check the sample sizes involved.
I have, so far, defined an "opportunity" as a ground ball hit with at least a runner on 1st base and there being fewer than 2 outs. That seems reasonable to me (for judging infields), but I may be overlooking something.
Operating under the assumption that I am not, I obviously wanted to see how the Mariners fared by this measure. I figured they'd be above average given the skills of Ryan and that, from my eyes, Dustin Ackley was also underratedly adept at turning two.
UZR on FanGraphs actually has a double play rating broken out for teams, and it lists the Mariners as being very good, actually the best, in the Majors at 7.5 runs above average. But I don't know the specifics behind calculating that number and I like to verify stuff myself. And though I'd wager our two methods are very similar, it's comforting to see the Mariners rank well in my exploration as well.
|Team||Team DP rate||Extra DPs turned||Runs|
On the ordinal ranks, this list and FanGraphs' UZR DPR are quite similar. The magnitudes on my end are quite heavier though. I can't say why since I don't know UZR's inner workings. Perhaps my weight for runs is off. I had previously calculated the run value of turning a ground ball into an out as 0.83 so I simply used that here. Maybe there's a better figure. That would change the magnitudes, but not the rankings.
You might notice a possible big split between the leagues. You would be correct. This might be a symptom of something overlooked in this rather simple model, but 12 of the 14 American League teams rank above the MLB average. The only two teams not were the Orioles (barely, 34.1% to 34.2%) and the Angels. Combined, the 14 AL teams were +80 runs here. It's curious. And to shoot down one possible hypothesis, no, bunts are not included in the double play opportunities, so the NL's penchant for more sacrifices shouldn't cause this.
Whilst digging further in the data, I categorized it a bit more into batter handedness and direction of the ground ball. I did that for many reasons but the two most probably interesting to others were 1) to see what differences emerged on a league level between trying to double up left-handed and right-handed hitters and 2) to see what differences emerged on a team level between grounders hit primarily to the short stop side (left) versus the second baseman side (right).
|Hitter stands||Hit to||Double play%|
|league rates, 2012|
Unsurprisingly, lefty hitters are harder to double up than their inferior right-handed counterparts. Percentages of converted double plays fell by about five points if a left-hander hit the ground ball. The drop was similar (4.7 vs 4.9) on both sides of the infield. I said unsurprisingly because left-handers have a shorter track to reach first base than do right-handed hitters and so intuitively they would be harder to force.
In the team ratings between balls hit to the left of the infield compared to the right, big differences emerged. Reassuringly, most of those differences conform to subjective impressions. Keep in mind this is not ranking the best of each side, it's just an ordering of the difference between double play rates to the left and to the right.
The biggest gaps favoring the left (short stop) side include the Athletics, Blue Jays, White Sox, Royals and Rangers. These make sense. The Athletics (Cliff Pennington, Jemile Weeks), the Blue Jays (Yunel Escobar, Kelly Johnson), the White Sox (Alexei Ramirez, Gordon Beckham) and the Rangers (Elvis Andrus, Ian Kinsler) all had starting short stops better regarded than the starting keystoners.
The biggest gaps favoring the right (second base) side include the Twins, Indians, Angels, Giants, Diamondbacks and Orioles. Most of those follow the same intuitive sense as above, but flipped, with more respected second baseman than short stops. Two that didn't fit that narrative were the Giants (where Pablo Sandoval at third might have played a role in making the left side look worse) and the Orioles (ditto with Wilson Betemit and Mark Reynolds).
|Hitter stands||Hit to||Leag DP%||M's DP%|
|league rates have M's numbers removed|
The Mariners showed almost no difference between the two sides when comparing against the league. I have the entire breakdown available in spreadsheet form here, if you care. You can look but not touch (edit), though you can copy and paste. Beware of the sample sizes in some of the situations. More hitters are right-handed than left-handed and most ground balls are pulled, so left-handers hitting a ground ball the other way, with a runner on first and fewer than two outs, just didn't happen all that frequently.
In case I haven't provided enough warnings and caveats yet, here's a final. These numbers are not adjusted for parks in any way. I do think that parks can play a role. For instance, the length and type of the infield grass can speed up or slow down ground balls which could increase or decrease the odds of double plays. It's a bit complicated and for the moment, I've left that for the future.