Mookie Betts Is Better Off Without His Strikeout Streak

Mookie Betts put together an incredible run of plate appearances without striking out, but was he actually a worse hitter during the streak?

September 12th, 2016 was an ordinary day in the MLB -- the Boston Red Sox met the Baltimore Orioles in an American League East clash in which Boston prevailed 12-2. However, it wasn't just like any other game.

Before his at-bat in the fourth inning on Wednesday night against Francisco Liriano, that date marked the last time outfielder Mookie Betts struck out in the regular season.

A lot happened between these two punchouts -- America saw a new President take office, the Chicago Cubs actually won a World Series, and 220 days, 1 hour and 41 minutes elapsed in total. Betts’ streak, which lasted 129 plate appearances, was the longest in the majors since Juan Pierre went 149 plate appearances without going down on strikes 13 years ago.

Naturally, we'd assume results would follow with a streak such as this, whether we're talking about real life or fantasy. Somewhat confusingly, though, Betts' production during the streak -- relative to his lofty standards -- wasn't that great.

Power Outage

To compare his production before the streak started and once he stopped striking out, the below table is split up into two time periods. The "before" spans from the start of the 2016 season to that September day mentioned above, and the "after" spans from when his streak started to present day.

We're specifically looking at his changes in Isolated Power (ISO) and various batted-ball metrics, such as line drive rate (LD%), ground-ball rate (GB%), fly-ball rate (FB%), soft-hit rate (Soft%) and hard-hit rate (Hard%).

Season PA AVG ISO BABIP GB/FB LD% GB% FB% Soft% Hard%
Before 653 .313 .232 .318 1.028 18.9% 41.1% 40.0% 16.8% 34.3%
After 132 .353 .101 .345 1.432 23.7% 44.9% 31.4% 19.5% 31.4%

The first thing that jumps out here is the glaring difference in Betts' ISO, which helps measure a hitter's raw power. Prior to the streak, he was performing as one of the league's best power hitters, but he registered an extra-base hit just eight times once the streak began. A reason behind that can clearly be seen in some of the batted-ball metrics highlighted above.

Betts' line-drive rate spiked, which is great, but his ground-ball rate also rose while his fly-ball rate took a dip, which obviously put a cap on his power. It also didn't help that his hard-hit rate decreased and coincided with an increase in soft-hit rate. So, fewer balls in the air and weaker contact overall doesn't help a hitter produce powerful results.

It didn't impact his BABIP negatively, though -- it actually increased from .318 before the streak to .345 after the streak began. That good fortune helped his batting average stay rather high, but there wasn't as much meat to that number as there had been leading up to it.

Plate Discipline Trends

So, what was causing this noticeable lack of power? There were some interesting trends to note in his plate discipline, specifically on pitches he was chasing out of the strike zone (O-Swing%) and on ones he was attacking in the strike zone (Z-Swing%), along with their corresponding contact rates.

Season O-Swing% Z-Swing% O-Contact% Z-Contact%
Before 25.3% 58.9% 70.9% 94.9%
During 26.4% 55.3% 80.3% 95.2%

During a strikeout streak such as the one Betts was on, one would imagine that his plate discipline would've gone in the opposite direction it actually went in. This provides the perfect explanation behind his power outage, though.

His contact rates went up in both instances, but much more drastically on pitches out of the strike zone. That enabled Betts to avoid strikeouts, but it also shouldn't be surprising to see his power disappear and the soft contact to increase.

So, even though the strikeout streak was incredibly impressive, he was less productive from a power standpoint. His first full game with the streak in the rearview mirror came on Thursday, and even though he struck out twice in four at-bats, he won the game for Boston in the 10th inning with a three-run double.

It looks like he'll be just fine.