Whether it's juiced baseballs or an increase in launch angles or hitters taking more of an all-or-nothing approach at the plate, players are hitting home runs and striking out at a record pace this season.
The 1,101 homers hit in June were the most in any calendar month in major-league history and 32 more than the previous high of 1,069 homers hit in May 2000, the peak of baseball's so-called "steroid era." The 1,060 homers hit this May are the third-most in any month.
Of the 25,382 hits this season through Saturday's games, 3,657 of them, or 14.4%, were home runs, the highest rate in baseball history.
Strikeouts are also on the rise, with players whiffing 21.6% of the time this season, according to Fangraphs. The strikeout rate of 21.1% in 2016 was the highest ever recorded and marked the third straight season it has topped 20%.
Which brings us to the curious case of Mookie Betts, the Boston Red Sox right fielder who is something of an anomaly in a sport where so many players are adjusting swing paths to better lift and drive the ball with little regard for strikeouts.
Betts, a two-time All-Star and runner-up to Mike Trout in American League most valuable player voting in 2016, leads his team with 17 home runs, 60 RBIs and an .843 on-base-plus-slugging percentage, and his 31 doubles are the most in the AL.
He hit .318 with an .897 OPS, 31 homers, 42 doubles, 113 RBIs and 122 runs last season.
The 5-foot-9, 185-pound Betts, in his fourth season, has the numbers and ferocious swing — if not the size — of an elite slugger. Unlike so many of his peers, he has not sacrificed a shred of contact or plate discipline for power.
Betts has a solid .280 average and .357 on-base percentage, and he has more walks (47) than strikeouts (40) in 96 games, a rarity for a power hitter.
Only three other players who have hit at least 12 homers this season have more walks than whiffs — Cincinnati's Joey Votto (26 homers, 71 walks, 49 strikeouts), the Chicago Cubs' Anthony Rizzo (23 homers, 55 walks, 50 strikeouts) and Washington's Anthony Rendon (20 homers, 55 walks, 51 strikeouts).
"You see a guy who takes pride in being a complete player," Red Sox manager John Farrell said of Betts during a weekend series in Angel Stadium. "That combination of bat-to-ball ability with power is what begins to separate him and put him in the conversation with a handful of the best players in the game."
Though Betts has batted third or fourth in 74 of 318 big-league starts, he doesn't see himself as a middle-of-the-order slugger, a perception that was reinforced by his early May move from third to the leadoff spot.
"I just kind of stay in my lane," Betts, 24, said. "I'm not a home-run hitter. I can't hit the ball out of the park to all fields and do those types of things. I score runs. I try to get on base and let the guys behind me hit me in."
Betts' average launch angle, according to Statcast, has fluctuated a bit over the last three seasons, from 14.8 degrees in 2015 to 12.5 degrees in 2016 and back to 14.8 degrees this season. The major-league average this season is 10.9 degrees, up from 10.1 in 2015 and 10.8 in 2016.
But Betts has not made a conscious effort to use more of an uppercut. The launch-angle increase this season is because of his career-high 14.7% pop-up rate, which is twice as high as the major league average and a result of Betts' occasional slumps in which he loses the timing and rhythm of his swing.
"I have no idea what my launch angle is, but no matter what it is, I'm still not going to be able to hit the ball out of the park much due to my size," Betts said. "If I try to do those kinds of things, I'm gonna be crushing balls and hitting them to the warning track. Those are outs."
Not all the time. Betts' bat speed, strength and ability to barrel up a baseball has sent plenty of those drives over the wall.
"He's hit some line drives that have gone out of ballparks where you just shake your head, because he's not a physically imposing player," Red Sox bench coach Gary DiSarcina said. "He's what, 185 pounds? He looks like he could be a second baseman."
Betts was a second baseman when he was first called up, starting 14 games there in 2014 before moving to the outfield. After playing center field in 2015, Betts shifted to right to make way for Jackie Bradley Jr. Betts leads all major league players with 24 defensive runs saved this season.
"All he wants to do is get better," Farrell said. "That drive, combined with his physical abilities, is a pretty rare thing."
So is his resistance to strikeouts. Betts went 129 plate appearances over 29 games from Sept. 12 to this April 20 without a strikeout, the longest-such streak since Florida's Juan Pierre went 147 plate appearances without a whiff in 2004.
But it's not as if Betts is a slap hitter looking to put the ball in play and use the speed that has allowed him to steal 17 bases this season. He hit .360 with an .881 OPS, two homers, five doubles and 14 RBIs during his strikeout-less streak.
"The beautiful thing is if you walk him, he can steal a base," Boston hitting coach Chili Davis said. "So that's gonna make them throw strikes to him."
Betts' strikeout rate of 8.9% is less than half of the major-league average. His contact rate — the percentage of contact made when swinging at all pitches — of 86.1% is nine points higher than the big league average of 77.6%.
His swing-and-miss rate of 5% is less than half of the major-league rate of 10.4%. And while he goes into "a more protective mode" with two strikes, the numbers don't reflect that.
Betts is batting .240 with a .297 OBP and .382 slugging percentage, four homers, 17 doubles and 27 RBIs with two strikes this season. The average major-league slash line with two strikes: .176/.249/.281.
Friday night against the Angels, Betts fought off a nasty 2-and-2, down-and-away slider from Ricky Nolasco and drove an RBI single to left.
"He's a good hitter, and it doesn't go to his head," Davis said. "He gets happy when he does something good, but his focus is on getting better. And sometimes he's getting better, and he's still trying to do better. That's fun to work with."
Betts doesn't possess the pure power of Trout, who, at 6-2 and 235 pounds, has a distinct size advantage over the Red Sox star. But Betts' combination of speed, power, production and superb defense — and the fact he finished second in MVP voting last season — puts him in a similar class.
"The comparison to Trout is fair, but it's not fair," said DiSarcina, the former Angels shortstop and third-base coach. "They're two different body types, two different types of players.
"But what they both do really well is they get in that batter's box and change the momentum of games in different ways, whether it's a home run or a two-strike, two-out knock that scores somebody."