Aggressiveness paying off for Red Sox hitters

In both 2013 and '16, the Red Sox won the American League East after finishing in last place the year before. No such rebound is needed this season -- Boston captured its second straight division title in '17 -- but the club might be executing a different sort of bottom-to-top jump.
Despite their success in 2017, the Red Sox finished last in the AL in home runs (168) and next to last in slugging percentage (.407). While there certainly were many reasons for this surprising lack of thump, from injuries to the profound absence of David Ortiz, there was one that stood out as both dramatic and potentially fixable.
And so far in 2018, Boston is indeed fixing it.
By several measures, last year's Red Sox had MLB's least-aggressive lineup against hittable pitches, with Mookie Betts and Xander Bogaerts serving as two of the main culprits. Patience, of course, can be a virtue at the plate. But there's a difference between being selective and being passive, and Boston hitters perhaps strayed too far toward the latter.
With Statcast™'s detailed strike zone, we can separate pitches that are clearly within the zone from those on the edges or outside of them. In 2017, Major League hitters slugged .593 on swings in the first category, compared with .385 in the second and just .150 in the third. Yet when the Sox got those favorable pitches inside the edges of the zone, they didn't take full advantage.
Lowest swing rate on pitches inside edges in 2017
1. Red Sox: 66.7 percent

2. Marlins: 69.7 percent
   
3. Rangers: 69.8 percent
   
4. Blue Jays: 69.9 percent
   
5. Mariners: 70.0 percent
   On an individual level, Betts (57.1 percent) and Bogaerts (58.1 percent) had two of the five lowest rates among the 168 batters who saw at least 500 pitches inside the edges. As a team, Boston also posted the lowest swing rate on those pitches in 0-0 counts (35.1 percent) and the lowest rate on pitches right down the middle (71.6 percent).
   Enter new manager Alex Cora, who led a concerted effort to change that approach.

Immediately, in his introductory news conference, Cora talked about "hunting pitches you can do damage with," and said his players would be ready to do so, even early in the count. And Cora singled out Betts and Bogaerts as hitters who could improve in this way.
"We're going to preach them to be aggressive," Cora said. "Not everybody has to take pitches. I get it. Work the count. But is it worth it to work the count now? Guys are throwing 98, 99. So you hunt for a pitch available and you do damage with it. That's going to help us out."
Words at a press conference don't always lead to actions on the field. But, at least over the first two weeks of the season, the Red Sox seem to be following Cora's lead.
Highest swing rate on pitches inside edges in 2018

1. Orioles: 76.6 percent
   
2. Giants: 76.1 percent
   3. Red Sox: 75.4 percent
   
3. Twins: 74.5 percent
   
4. Cubs: 74.1 percent
   It helps that Boston's big free-agent acquisition, J.D. Martinez, attacks these favorable pitches about as frequently as anyone. He had one of MLB's highest individual swing rates on them last year, and he is No. 1 this year (89.5 percent) among those with at least 50 pitches seen.

But it's also about the holdovers taking the shift in strategy to heart. In terms of swing rate against pitches inside the edges, Rafael Devers (+14.8 percent), Bogaerts (+17.0 percent), Hanley Ramirez (+8.7 percent) and Betts (+5.2 percent) are among the Red Sox who have posted the biggest increases from 2017 to '18.
Boston also ranks third in the Majors in highest first-pitch swing rate against pitches inside the edges (56.6 percent), as well as first in swing rate against down-the-middle offerings (83.9 percent).
Cora has used different tactics with different players, but with Betts, he was direct. Betts remembers taking a call from his new skipper right after he was hired, and that one of the first things Cora talked about was approach at the plate. Cora also has showed Betts his swing percentage numbers, with the basic message being to "swing more often."
While early-season caveats apply, it's working. Boston improved to 10-2 with Thursday night's win over the Yankees, and the club ranks third in the Majors in runs scored per game (5.75) and sixth in slugging (.421).

Betts is off to a torrid start, posting a .370/.455/.630 slash line and leading the Majors with nine barrels -- batted balls with an ideal combination of exit velocity and launch angle. Before going on the 10-day disabled list Monday, Bogaerts produced a .368/.400/.711 line, while matching his barrel output (six) from the entire 2017 season. Of those 15 combined barrels by Betts and Bogaerts, 13 have come against those inside-the-edges pitches, including a grand slam by each player.
The season remains long, of course, and good habits can slip. But if the Red Sox maintain their newly discovered selective aggression, it may bode well for the fate of their offense in 2018.