It’s been quite some time since we’ve heard any public outcries regarding the new turf in the Rogers Centre. The turf, which was installed prior to this season, became a topic du jour in the early going of the season, as seemingly every opposing team that lost a road series to the Blue Jays had a complaint regarding the supposedly unfair advantage the turf gave the Blue Jays.

Owen Watson explored this issue at FanGraphs back at the end of April, and the numbers downplayed the impact of the turf on balls in play. However, now that we are just under a month shy of having a full season’s worth of data, the effects of the turf have become amplified.

By now, it’s not a secret the Blue Jays are really good. As I write, BaseRuns has them pegged as the strongest team thus far on the back of the best offense in baseball by quite a fair margin; their 5.42 runs per game are almost 0.7 higher than the next best offense. The pitching staff is more pedestrian, placing 14th in baseball in FIP-WAR. They do, however, just crack the top 10 in RA9-WAR. The Jays’ pitching staff’s .283 BABIP is the fifth-lowest mark in baseball this year.

Let’s see if we can dissect that BABIP to analyze what kind of impact the Rogers Centre has had on that figure. Here are the BABIPs of Jays pitchers who have started at least 10 games thus far, as well as their home vs. away splits.

Those are some pretty substantial gaps. While BABIP is certainly not the stickiest stat out there, a gap this large and universal—especially in conjunction with a change to the stadium—merits further exploration. Perhaps the Jays pitchers always have suppressed BABIP at home. Let’s look at their splits over the last three years.

BLUE JAYS PITCHING STAFF BABIP, 2013-2015 Year Home BABIP Away BABIP 2013 0.290 0.297 2014 0.290 0.297 2015 0.258 0.305

Given the consistency between 2013 and 2014, it seems fair to say the turf has had a non-negligible effect on the frequency at which balls in play become hits. To this point, however, I have explored only one side of the equation. It remains to be seen whether the Blue Jays’ hitters have experienced the same effect as their pitchers have. Let’s repeat the previous exercise for Toronto hitters.

BLUE JAYS POSITION PLAYER BABIP, 2013-2015 Year Home BABIP Away BABIP 2013 0.289 0.280 2014 0.306 0.285 2015 0.297 0.291

While this outcome is not as clear-cut, the fact that 2015’s split is the lowest among the three years and is below league average for a home team demonstrates that Rogers Centre has played as an environment that is much less friendly to balls in play. Given that the only publicized change to the park was the installation of new turf, it also follows the only substantial impact would be on ground balls.

Moreover, that the Blue Jays’ pitchers’ split is much more exaggerated than that of their hitters gives some credence to the early-season complaints, in that the Blue Jays have been more effective at using this abnormality than their competition. To accuse the Blue Jays of foul play, however, seems premature. It is entirely possible their roster was constructed to maximize the effect of the turf by focusing on groundball pitchers, infield defense, and flyball hitters. Let’s look at the batted-ball profiles of the Blue Jays’ hitters and pitchers at home to see if any of these ideas hold true.

BLUE JAYS BATTED BALL PROFILES, 2015 Position Group LD% GB% FB% Hitters 19.5% 44.7% 35.9% Pitchers 20.4% 43.8% 35.8%

The splits are almost identical, so the difference between the Blue Jays’ hitter and pitcher BABIPs at home can’t be chalked up to batted-ball distribution. What this suggests is that a fair bit of the credit needs to go to the fielders. Since they play more games in the Rogers Centre than any visitors, Toronto fielders would appear to be best suited to succeed in such an extreme infield park environment.

This effect is likely a combination of positioning and ability to judge how a ball may roll differently on the turf. This also provides a reasonable explanation for why the results were more neutralized when Owen explored the topic in April, as the Blue Jays’ infielders did not have a substantially larger sample of playing time with which to learn the nuances of the new turf.

The Rogers Centre always has been relatively dinger-friendly, which suggests flyball hitters like Jose Bautista, Edwin Encarnacion, Josh Donaldson and Troy Tulowitzki are tailor-made for the Rogers Centre. When you also consider that ground balls are less likely to become hits, the arbitrage flyball hitters represent in the Rogers Centre is fortified even further. Let’s examine how these sluggers have fared this season in terms of home vs. away BABIP.

SELECT BLUE JAYS HITTER BABIP SPLITS, 2015 Name Home BABIP Away BABIP Jose Bautista 0.222 0.235 Edwin Encarnacion 0.263 0.267 Josh Donaldson 0.362 0.276 Troy Tulowitzki 0.333 0.237

While Bautista and Encarnacion seem to fall within reasonable variance of the average split, the one who jumps off the page here is Donaldson, whose substantially positive split runs counter to the notion that the Rogers Centre suppresses BABIP. Perhaps Donaldson is getting lucky—heck, there’s always that possibility when we are talking about BABIP, especially before it reaches its stabilization point. After all, he’s never been a high-BABIP type of hitter, with a career mark of .303. Or maybe Donaldson is doing most of his damage on line drives and fly balls, which still allows for the possibility of luck. (Tulowitzki’s numbers also jump off the page, but his sample size with the Blue Jays is much more limited.)

It would, however, suggest his numbers aren’t due for as steep a regression as they would if his numbers had been shattering the mold of low BABIP on grounders in the Rogers Centre. This would imply that the impact of the turf would catch up with him and normalize his home BABIP going forward. Let’s look at where Donaldson has done the most damage this year in comparison to his past two years in Oakland.

JOSH DONALDSON BABIP SPLITS, 2013-2015 Year GB BABIP FB BABIP LD BABIP 2013 0.264 0.136 0.781 2014 0.306 0.140 0.556 2015 0.251 0.158 0.753

While it’s important to be careful with the sample size, we shouldn’t be too surprised by the slight drop in BABIP on grounders. While the flyball BABIP has increased, the column that stands out here is BABIP on line drives. The large variance among the three years likely accounts for Donaldson’s large swings in overall BABIP.

While luck certainly could play a role, the new batted-ball stats from Baseball Info Solutions can provide us with some insight as to whether Donaldson has been hitting his line drives with more authority this year than in years past. Here’s a breakdown of his hard percentage on line drives over the past three years.

JOSH DONALDSON LINERS HARD%, 2013-2015 Year Liners Hard% 2013 45.9% 2014 52.3% 2015 56.2%

Donaldson is hitting the ball harder than ever on his line drives, which seems to back his high BABIP on such contact. This makes Donaldson’s 2015 BABIP look much more sustainable than that of 2013. Donaldson is neutralizing the effect of the new turf on BABIP by doing substantial damage on balls hit out of the infield.

While the 75-point home vs. away split likely could be chalked up in large part to small sample size, he is hitting the ball harder at home (38.8 percent Hard%) than away (35.2 percent), and as Owen Watson noted back in July, Donaldson is pulling balls more frequently at home. Thus, while it would be aggressive to expect such a large split to continue going forward, it would be similarly shallow to assume the Rogers Centre’s turf’s effect on BABIP will annihilate his high BABIP on line drives.

In the midst of a torrid stretch that has vaulted the Blue Jays into first place in the AL East, Donaldson’s MVP candidacy has jumped to the forefront of the discussion. And while the Blue Jays’ otherworldly offense, centered on Donaldson, deserves much of the credit, their home park (and the way their defense has adapted to it) deserves a mention as well.

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