This week marks the halfway point of the regular season. I don't know about you, but for me time has flown by! It must be another consequence of the pitch clock.
This is also the time of the year many take stock of their fantasy baseball squads to decide how to approach the second half. Where is my team weak, and where do I have a surplus? Are any trades in order? Perhaps most importantly, it's time to assess both those who are underperforming on your roster as well as identifying players who are "out over their skis." Preparing for a fall can help soften the blow.
It has become mainstream to analyze pitching by comparing "actual statistics" to an expected version. The most common metric put under the microscope is ERA, as there are several easily accessible expected ERA formulas such as FIP, xFIP and SIERA, along with Statcast's xERA. Though they all have differing inputs (with some overlap), they all translate skills to what "should have happened." A significant difference between actual and expected stats often indicates that regression is forthcoming. A pitcher with an ERA below what was expected is probably going to post a higher ERA going forward, while someone with an ERA above what was expected will probably enjoy better days ahead, assuming little-to-no change to their skills.
Hitters can be evaluated in a similar manner. The frequency of contact (as well as the type of contact), yields expected outcomes. If a hitter's numbers differ greatly than expected, then they are candidates for some regression -- just like with pitchers and ERA.