Aaron Hill hit 62 home runs between the 2009 and 2010 seasons. It took him just two years to over triple the home run output of more than 1800 prior plate appearances.
Hill is just one beneficiary of Rogers Centre’s kind left field, a list that now includes Jose Bautista, Edwin Encarnacion and apparently Jeff Mathis. The main difference between pre-2009 Hill and post-2009 Hill was a change in fly ball rates — an increase of about seven percentage points. By lofting the ball and utilizing that left field, Hill turned from an unremarkable contact-hitting second basemen into an elite power force at the position — for reference, Robinson Cano has 61 home runs over the past two calendar years (covering 320 games).
Hill and Cano are similar hitters before contact — each have slightly below average walk rates and very good contact rates — but Hill lacks the raw power and distance Cano possesses. Cano used just a 29.7% fly ball rate to get to 61 homers, exactly 17 points lower than Hill needed for just one more dinger.
There is a cost to hitting more fly balls: fewer hits. Cano uses his raw power to hit more of his fly balls out of the park, possessing a 20.1% HR/FB the last two years compared to Hill’s 12.9% from 2009-10. And so with fewer fly balls hit in play for Cano, he takes less of a ding from the .138 leaguewide BABIP on fly balls. In the majors, if you get the ball up in the jet stream, it better be carried over the fence.
Hill posted a horrific .196 BABIP in 2010 despite the 26 home runs, leading to a .205/.271/.394 (76 wRC+) line. His second season as Power Hitting Second Baseman Aaron Hill saw him overdo the fly ball approach which led to his 2009 breakout (.286/.330/.499, 114 wRC+). His fly ball rate skyrocketed to 54.2% — a 13-point increase — which meant an equal number of fly balls (241) as in 2009 despite 154 fewer plate appearances.
But Hill couldn’t squeeze as much out of those fly balls, and it should be no surprise — his 14.95% HR/FB rate in 2009 was a career high by six points, and it regressed back to 10.8% in 2010. Hill was hitting the ball hard — his average home run went off the bat at 102.3 MPH in 2010 compared to 101.9 in 2009. A possible explanation? He was lofting the ball too much. He also had a higher average launch angle (29.1 degrees vs. 28.6) on his homers in 2010 than in 2009 and the same true distance (387.2 feet).
That’s how this:
In 580 plate appearance in 2010, Hill produced 192 fly ball outs. In 80 fewer plate appearances this season, Cano has made just 63.
Hill limped through the 2011 season with Toronto, posting a .225/.270/.313 line in his 104 games as a Blue Jay. But a change of scenery saw a return to the ways of 2009: hard line drives and fly balls (29.5% LD%, 37.1% FB% in 33 games — likely a few typical fly balls earned line drive classification) leading to a .492 slugging percentage in another friendly park in Arizona.
This season, the 30-year-old Hill has a healthy fly ball rate at 45.3% and has a decent chance at his third career 20-homer season — he sits at 14 currently with ZiPS projecting five more down the stretch. He will never quite match Robinson Cano or his ilk in terms of power, at least not while maintaining an acceptable batting average and on-base percentage. His swing just doesn’t have the power to sneak enough fly balls over the fence.
And so balance is required. Enough fly balls to make his power count, enough ground balls to keep getting on base. Hill has that balance now in Arizona, and the result — even if he’s no Robinson Cano — is one of the most productive second basemen in the league.