Meet the secret source behind the Blue Jays' power surge

Going into the 2015 season, we had a pretty good idea that the Toronto Blue Jays were going to hit a lot of home runs. After all, they hit the third-most home runs in baseball during 2014, and then added Josh Donaldson. The pieces were there for a huge offensive season from the entire team. But even with the talented personnel and a hitter-friendly home stadium, 2015 was the kind of season that was probably on the high-end of expectations. The Jays hit 232 home runs, the most by any team since the Yankees hit 245 in 2012.

As Matt Snyder pointed out in late September, the 2015 Blue Jays were only the 14th team in major-league history to have three players with 35-plus home runs each, and were the first team to have three since the 2006 White Sox. Those players, of course, were Donaldson, Jose Bautista and Edwin Encarnacion. Digging deeper into the stats, the offensive approach shown by those players at the Rogers Centre was a driving force behind the team's power explosion.

By July, we had a sense that Donaldson was intentionally altering his plate approach at home to hit more homers: He was striking out more, walking less and pulling the ball far more often when playing at the Rogers Centre than on the road. In short, he was being ultra-aggressive at the plate when at home, and it turned out to be a big part of what would become an MVP season for the third baseman. A quick look at the increase in his pull rate at home in 2015 when compared to 2013 and 2014 tells a big part of the story of his year:

Big power seasons often follow short-term increases in pull tendencies, and Donaldson was no different. And, looking further down the lineup, he wasn't alone in changing his approach to get the most out of playing in Toronto's hitter-friendly environment during 2015. Donaldson's main partner in adopting these more aggressive changes was Bautista, who showed a few important tweaks to his Rogers Centre approach between 2014 and 2015. He pulled the ball in Toronto more than he ever had before, owning the third-highest change in pull tendency out of all qualified hitters when at home. Take a look at the rate of balls in play he pulled at home vs. on the road over the past five seasons:

Bautista posted his highest pull rate at home in the past five seasons during 2015, pulling over 5 percent more batted balls than his previous high in 2013 -- and possessing a higher pull percentage at home than on the road for the first time since 2010. He also hit the most flyballs at home since 2012:

Pulling the ball in the air is what power hitters tend to do, but it's the amount of change in these numbers between previous seasons and 2015 that is so eye-catching. Given the fact that Donaldson and Bautista already had great power numbers before 2015, these large changes in approach seem to be intentional.

This is usually the time when we search for instructions or indications that something has changed with the hitting coach. For the Jays, that man is Brook Jacoby -- the fourth Toronto hitting coach in four years and owner of an 11-year playing career in Atlanta, Cleveland and Oakland. While I couldn't find any quotes directly pointing to him instructing Jays hitters to be more aggressive to the pull side and hit more balls in the air, we can glean some information from his role in helping Ryan Goins become a major-league hitter during the second half of last season.

One quote from this article in the National Post stands out, as Goins explains the difference between life under former hitting coach Kevin Seitzer compared to Jacoby (along with Jacoby's assistant hitting coach Eric Owens):

"In my case last year, it was 'take pitches, hit the ball the other way all the time,' " Goins said. "It wasn't what I felt comfortable doing. It wasn't what got me here. Then this year I come in and they both say, 'Do what you want, and if you have questions, ask and we'll help.' "

While we can probably be confident Seitzer didn't tell Bautista to hit the ball the other way very often during 2014, this is telling as to how the Jays hitters were coached the past two seasons. If we listen to Goins, the coaching in 2014 was more heavy-handed; in 2015, it was more relaxed. The Toronto hitters were allowed to be who they wanted to be, and for the power hitters -- namely Donaldson, Bautista and Encarnacion -- that meant pulling the ball in the air more often, especially in a home park they knew was kind to that approach.

That narrative fits with Jacoby's own thoughts on Donaldson's approach in this article from the Toronto Sun during late March of this past season:

"I like the way he attacks the baseball. ... You don't see him half in or half out. He's all in. When he makes his mind up to swing, he lets it go."

Baseball is filled with these sorts of platitudes, and at face value, a quote like this might not really register. But if we dig deeper into that article and listen to how Jacoby speaks about each particular hitter on the team, we start to get a sense of the way he approaches coaching: Let hitters be who they naturally want to be, and deal with any minor mechanical adjustments as they come up. Don't try to mold them into someone they're not. It's a wildly obvious coaching mindset, but Toronto just posted far and away the best offensive year out of any team in baseball. Something is working.

Perhaps it's not too much of a surprise that this coaching approach could yield such a successful offensive season with the type of veteran hitters the Jays have in their lineup. They all know who they are and what they want to do. As we can see above, Donaldson and Bautista post flyball and pull rates far above the league average, and Encarnacion does as well. Maybe 2015 was simply the manifestation of an ideal for the middle of the Jays lineup, the latest season in a few careers that are built around the identity of premier power hitting. As crazy as it sounds, maybe they needed less coaching. Perhaps Jacoby simply let them do what they've always wanted to do: hit a historic number of home runs.