Author Archive

Potential Starting Pitcher HR Rate Improvers — May 26, 2021, A Review

We’re finally winding down the in-season metric reviews, and today, we return to Statcast’s xHR calculation, but this time for pitchers. So we’ll be reviewing the pitchers that had allowed significantly more home runs than expected according to Statcast through May 24 and find out how each performed over the rest of the season. Like I did for my hitter review, this is essentially comparing HR/FB rates through the first two months with the rest of the season, since actual fly balls are used in the calculation and Statcast is calculating how many of those should have left the park versus what actually did. Let’s find out if these pitchers did enjoy major HR/FB rate improvement over the rest of the way.

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Potential Batting Average Decliners — May 20, 2021, A Review

Yesterday, I reviewed the hitters who most underperformed their Statcast xBA marks through May 17. All but one posted a stronger batting average the rest of the way. Now let’s flip over to the overperformers — those hitters who posted batting averages significantly above their xBA marks.

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Potential Batting Average Surgers — May 19, 2021, A Review

Today, I move on to reviewing the list of biggest batting average underperformers through May 17, according to Statcast’s xBA. As usual, xBA isn’t perfect, as it ignores anything shift-related, but it’s good enough that if you stick with the players on the extremes (largest BA-xBA gaps), I would imagine the rest of season directional moves should be expected. Let’s find out if that was the case.

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Hitter Statcast xHR Overperformers — May 11, 2021, A Review

After reviewing the early season Statcast xHR underperformers yesterday, let’s now review the early season Statcast xHR overperformers today. Once again, I’ll compare each hitter’s HR/FB rate through May 9 to his mark over the rest of the season.

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Hitter Statcast xHR Underperformers — May 10, 2021, A Review

As I wind down my in-season metric reviews, I now move along to Statcast’s xHR calculation. In early May, I shared a list of hitters whose xHR total was at least one home run more than their actual totals. I wasn’t entirely sure what the best way to review how this group performed over the rest of the season, so I settled on HR/FB rate through May 8 versus the rest of the season. I ruled out AB/HR because strikeout and fly ball rates influence that rate and a homer can only be hit if the ball is put into play and isn’t on the ground.

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Starting Pitcher SIERA Overperformers — May 6, 2021, A Review

Yesterday, I reviewed the early season starting pitcher SIERA underperformers and discovered that the majority did indeed improve their ERA marks over the rest of the season, some significantly so. Now let’s flip over to the list of SIERA overperformers. Were these pitchers able to sustain their magic or did the force of regression prove too powerful?

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Starting Pitcher SIERA Underperformers — May 5, 2021, A Review

Today, I’ll review my favorite in-season ERA estimator, SIERA. This was the list of SIERA underperformers through May 3. The idea here was that absent a significant change in underlying skills (K%, BB%, batted ball profile), these pitchers should post much improved ERA marks the rest of the way as their luck metrics (BABIP, HR/FB, LOB%) normalize. Let’s find out if that did indeed happen.

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Hitter xwOBA Overperformers — May 4, 2021, A Review

Yesterday, I reviewed the list of hitters who most underperformed their xwOBA marks through May 1. All but two of the 11, who had already posted actual wOBA marks over .400, improved their wOBA marks over the rest of the season, some quite dramatically. Let’s now review the hitters who most overperformed their xwOBA marks through May 2 and find out how many of them did indeed suffer a wOBA decline through the rest of the season.

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Hitter xwOBA Underperformers — May 3, 2021, A Review

Today, I continue my in-season metric lists with a review of the xwOBA underperformers through May 1. We know that xwOBA isn’t a perfect metric of what a hitter “deserved”, nor is it meant to be predictive. However, it’s certainly better to use it than wOBA itself when trying to forecast rest of season performance. This is especially true when only a small sample of games are in the books, so expected metrics play a more valuable role. So let’s find out how this group of hitters performed over the rest of the season.

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Starting Pitcher GB% Decliners — Apr 22, 2021, A Review

Yesterday, I reviewed the starting pitchers who experienced an early season GB% surge to find out if those spikes were sustained over the rest of the season. Today, let’s now review the early season GB% decliners. Did their GB% marks rebound or remain down, increasing the risk of gopheritis? Let’s find out.

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