A's Jacob Lopez Made a Key Change Against Philadelphia Phillies

When the Athletics acquired 27-year-old left-hander Jacob Lopez from the Tampa Bay Rays as part of the Jeffrey Springs deal, A's GM David Forst said that they still saw Lopez as a starting pitcher. Headed into Friday's game against the Philadelphia Phillies, just one of the southpaw's four appearances in green and gold had been as a starter.

Last night, with the injury to J.T. Ginn, Lopez got his chance to put himself in that mix, and he made the most of the opportunity he was presented with, going seven innings against the sixth-best offense in the month of May.

Following a lead-off home run to Trea Turner, Lopez was able to really lock in, giving up a total of three hits, so two after the home run, walking one, hitting one, and striking out eight. That was the most strikeouts by an A's starting pitcher all season.

The trick may seem fairly simple, but it was pretty effective. In his previous outings this season, Lopez had been sitting primarily with his four-seam fastball (53.5%) and his slider (32%). This includes his 2.2 inning start against the Texas Rangers in Texas on April 29. Those two pitches were accounting for 85.5% of his arsenal, with his cutter (7.6%) and changeup (7%) rounding things out.

On Friday, he was mixing his pitches a lot more effectively. His four-seamer was still the main weapon, but he used it a bit less, at 43%. The slider was still the second-most frequent offering, at 29%, as well. But for you math majors out there, you can see where this is headed. The cutter was also firmly in the mix this go around, with Lopez tossing 23 of them, good for 25% of his pitches.

He still worked in the changeup, but threw just three of them for three percent of his pitch mix.

The key here is that the slider and the cutter are similar pitches, being that they both move horizontally. The main difference between them is that the cutter is the harder of the two and moves less, while the slider is softer and breaks more. Lopez's slider averaged 78.9 miles per hour, while the cutter sat at 87. That'll mess with a hitter's timing.

The stat line said that the sequencing worked, but some of the other metrics from his start are also pretty impressive. Of his 91 pitches, 40 of them were swung at. Of those 40 swings, he recorded 15 whiffs, good for 38%. And it wasn't just one pitch doing the heavy lifting either. The fastball (7-of-16) had a whiff rate of 44%, while the slider (3-of-10) was at 30% and the cutter (5-of-14) ended up at 36%.

Part of the reason for this, despite his fastball sitting at 90 mph, is that his extension ranks in the 90th percentile. What this means is that hitters have less time to react to his pitches, which makes that 90 play up a bit.

It should also be noted that his velocity was up across the board from earlier in the season, with his cutter seeing the biggest spike at 1.7 miles per hour.

A's manager Mark Kotsay said of his starter's performance, "Phenomenal night for him. To get us that type of start, that's what we needed." His start was able to give the bullpen most of the night off, outside of a couple of leverage arms that haven't been used much of late in Justin Sterner and Mason Miller.

While this type of pitch usage is new for Lopez at the big-league level this season, he's been mixing his pitches well in the minors, including in his most recent outing with Triple-A Las Vegas where he went seven innings and gave up three earned while striking out ten just over a week ago.

In that start against the El Paso Chihuahuas, Lopez also used what Statcast classified as two sinkers, which could be an added wrinkle that we'll see in the big leagues before long.