Jack Morris and Ron Guidry would each win 20 games in 1983. On the 13th of August, the two squared off in front of more than 50,000 at Tiger Stadium with first place on the line. Big Game Jack went the distance, as was his custom, to outduel Guidry and give the Tigers a one-game lead in the American League East. At that point, five teams were within 2.5 games of first and many were expecting the division race to be a dogfight down the stretch. It wasn't. The Orioles went on a 30-7 run starting on that day to leave the pack on their way to a World Championship. Twenty-two-year-old Cal Ripken won his first MVP and the words ``Can't anybody beat the Birds?'' echoed throughout Tigerland.
On the day the Orioles clinched, Jerry Remy doubled off Tiger reliever Doug Bair during a Boston loss in Detroit. Remy was a contact guy who struck out in only 5.4% of his 647 PAs that season for the second lowest K-rate in the AL behind teammate Wade Boggs. Contact ability tends to limit dry spells, but Remy's double was his only hit in his last 32 career plate appearances at Tiger Stadium. To this day, the RemDawg has less than fond memories of the old ballpark. If you listen to him long enough, he'll eventually tell you about Sparky Anderson's sinker-ball pitchers and how many groundballs they got. And then he'll tell you how Sparky had the grounds crew soften the dirt in front of home plate until it absorbed baseballs like quicksand. As if that wasn't enough, Anderson also instructed the staff to make the infield grass tall and thick to give Trammell and Whitaker more time to get to ground balls. The approach worked. Throughout the 1980's, Tiger Stadium had a home run park factor that heavily favored batters, but an overall park factor that favored pitchers. Thank Sparky and the groundskeepers.
Things have changed. Last year Tiger pitchers had the second most strikeouts in the American League. This played a big role in Detroit allowing only 1843 ground balls which was the second fewest in the circuit. Detroit batters, on the other hand, hit 1970 ground balls which was a little above the ML average of 1949. Thus, the 2012 Tigers hit 127 more ground balls than their opponents. If Sparky could make the infield slower in the 1980s, then 2012 would have been a good year to make it faster.
Let’s look at some numbers. Last year major leaguers hit .243 on ground balls at home and .233 on grounders on the road. The Tigers hit .289 on their ground balls at home against .234 on their ground balls on the road. Could this be a case of home field familiarity helping guys see the ball better and hit it harder at home? Probably not. If we look at the other team we see the same effect. Tiger opponents hit .269 on their grounders at Comerica Park and .238 on their grounders against Tiger pitchers away from Comerica. Since there were 3813 ground balls hit in Tiger games last year the impact of sample-size noise is small. It seems that ground balls actually get through the Comerica infield faster, with or without Tiger defenders on the field, than they do on other major league surfaces.
The numbers away from Comerica are, by definition, averages over a number of parks. Let's start there and assume the ML average 10 point home/road differential referenced earlier. Then Detroit’s .234 average on grounders on the road translates to an expected .244 at home which the Tigers, by hitting .289, outperformed by 45 points. The opponent .238 average away from CoPa translates to an expected .228 in Detroit which the enemy hitters, by hitting .269, outperformed by 41 points. Perhaps, like Sparky's teams, the 2012 Tigers prepared the infield to obtain an advantage. In any event, the numbers across Tiger and opponent batters are consistent. The state of the Comerica Park infield added more than 40 points to a hitter’s average on ground balls compared to what we'd expect in an average park.
How did this affect some individual players? In a previous post I talked about Austin Jackson's historic BABIP and how his .370 average on ground balls last year was the highest in the majors since 2009. Austin hit .393 on grounders at home and .345 on the road for a 48 point differential. Since his final 2012 batting average was .3002, it's safe to credit head groundskeeper Heather Nabozny with helping AJax to his first .300 season.
Miguel Cabrera led Tiger hitters with 226 ground balls last year. He hit .343 on his grounders at home and .298 on the road for a 45 point differential. Notice a pattern? Now what if he'd only enjoyed an average 10 point home field bump and hit .308 on grounders at home? Under that scenario, Cabrera would have lost four hits at home and batted .323 for the year. Not bad, but then Mike Trout wins the batting title at .326 and history is forever altered. But a Cabrera Triple Crown is what went in the books. Just because of the way Heather keeps the Comerica infield.
Prince Fielder was second on the Tigers with 215 ground balls last year. Entering the 2012 season, the Prince had hit .220 on his 1155 career ground balls. And last year Fielder hit .209 on his grounders on the road. But on the ultra-fast Comerica surface, Mr. Fielder hit .320 on ground balls in 2012. If we play the same game that we did with Cabrera's numbers, then Prince loses 10 hits at home. His first career .300 season, at .313, turns into just another near miss at .296. Hopefully Prince got Heather something nice for Christmas.
What about Rick Porcello who easily led Tiger pitchers with 330 ground balls allowed? Jerry Remy credited Sparky with adjusting the Tiger Stadium infield day-to-day depending on who was pitching. If you can do that, then you'd want the extra-absorbant quicksand in front of home plate when you expect the opposition to hit more ground balls than Tiger batters. Such an expectation occurs just about every time that young Rick toes the rubber. But there's no evidence of such tinkering. Porcello allowed a .267 average on ground balls at home compared to a .214 average on the road. This is along the lines of the overall trend with Rick even suffering a bit more than expected due to the CoPa surface. Perhaps the speed of the Detroit infield has contributed somewhat to the Turner trade, the Sanchez signing, and the Pocello trade discussions.
Can we quantify the impact of infield speed on the bottom line? It's a tricky business, but for my beloved readers I'll give it a shot. As a start, let's give the infield surface credit for the rise in Detroit’s and their opponent's batting average on ground balls at Comerica relative to the expectation for an average park. Then we'll account for Detroit’s extra ground balls at home. This works out to about six additional Tiger hits relative to the opposition in 2012.
But there's more to it. The Tigers grounded into a major-league leading 156 double plays last year. With a runner at first and less than 2 outs, the Tigers hit .281 at home on grounders and .241 on grounders on the road. Once again, this lines up with the overall trend and works out to an extra 13 hits in these situations for the Tigers at home compared to on the road. Ground ball hits are nice for a couple reasons. For one, they're hits and, for another, they're not double plays. Along with the 13 extra hits came 12 fewer Tiger GIDPs at home.
Tiger opponents had 10 extra hits at Comerica on ground balls in double play situations compared to their home number which, once again, matches the overall trend. But while the Comerica suface yielded these extra ten hits, the Tigers turned only one fewer double play. I suspect that the incongruity of this observation with the last sentence of the previous paragraph relates to slow Tiger runners often needing to hit the ball all the way through the infield to avoid a double play and the slow-twitch Tiger infielders only being able to turn a fixed fraction of the easiest double plays. Let's be generous and give the infield surface credit for a plus eleven in reducing Tiger GIDPs at home relative to their opponents.
What are six more singles and eleven fewer GIDPs worth? If we plug in the average run values we get about 12 runs which, on average, works out to a little more than one win. For calibration, the Tigers had an overall 64-run advantage at home last year. But along with that extra win came a Triple Crown, an MVP, and .300 seasons for Prince and Austin. Not a bad haul for Heather and her crew.