This article is part of our The Z Files series.
One of the repercussions of the current pitching landscape is the need to make even snappier decisions when a pitcher goes on a hot streak. Is it real, or will he revert to his previous form? There was a time where sample size was the parachute. There isn't ample data, though, so why even try? This isn't to say we now have all the answers with Statcast and the like, but we can graduate from a dart throw to an educated guess.
Below are seven pitchers with solid July numbers, all an improvement over the first three months. Each will be put under the microscope with their underlying metrics dissected in order to judge the sustainability of their current performance level.
Reynaldo Lopez, Chicago White Sox
Lopez has been crushing it since the break. Some may point to the opponents (Athletics, Rays and Marlins) and contend he's taking advantage of weaker lineups, but that doesn't explain the marked difference in the quality of, and change to, his repertoire.
Over his last three outings, Lopez has added a couple ticks to his four-seamer, though the spin rate is about the same. Still, sitting 97 mph since the break has more than doubled his SwStr%, spiking from 8 percent to 17.6 percent.
Additionally, Lopez is throwing fewer changeups while edging up his curve and slider usage. Both latter offerings benefit from greater spin and sure enough, Lopez's spin rate on both is up several revolutions.
A 6.34 ERA before the break