With his Dodgers on the brink of advancing to the NLCS, manager Don Mattingly named Clayton Kershaw to start game 4. It will be his first-ever start with less than four days’ rest. Kershaw had one relief outing on three days’ rest back in 2008, at the end of his rookie year, allowing three baserunners in one inning, but no runs.

Since 2009, his first full year, Kershaw has 90 starts on four days’ rest and 71 starts with five or more days’ rest. Both sets show a 2.44 ERA and 1.05 WHIP.

I expect to add more to this post, but in the meantime, let’s get the argument started. Some pundits like this move. I hate it. What do you think?

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After a high-pitch game

Kershaw threw 124 pitches in game 1, his 3rd-highest total ever, which seems a big load to shake off on short rest. On the other hand, he had only one stressful inning, and that came with a 5-0 lead. But let’s look at his history in terms of coming back from his heavier pitch counts.

Overall, Kershaw’s pitch load is lower than most aces. He was kept on a short leash in his first two seasons, and since then he’s been so successful (leading the NL in WHIP the last three years) that he rarely throws 115 or more in a game. Since 2010, Kershaw’s 131 starts are just 3 off the lead, and his 901 IP ranks 4th — but his 24 games with 115+ pitches ranks 10th.

I figured the numbers for what Kershaw did in his next start, (a) after throwing 115+ pitches (24 games), and (b) after throwing 104-114 pitches (59 games). In each case, I omitted all starts on 7 days’ rest or more.

• After 105-114 pitches: 2.72 ERA … 2.88 RA/9 … 1.09 WHIP … 25.1% SO rate … 64 batters per HR … .317 SLG
• After 115-132 pitches: 3.86 ERA … 4.14 RA/9 … 1.11 WHIP … 24.5% SO rate … 40 batters per HR … .360 SLG

The WHIP and SO% are so close that it’s tempting to write off the big jump in runs as a sample-size blip, since the high-pitch group holds just 24 games. And that could be the truth — but note the HR and slugging rates. In the first group, 31% of his hits go for extra bases, but that’s up to 36% in the high-pitch group. Note that all of the high-pitch followers came in his “mature period,” since 2010, when he’s topped 200 IP and 200 Ks each year.

For completeness, I’ll repeat the numbers, adding a line for his 87 starts that followed a start of 104 pitches or less:

• After  <= 104 pitches:  2.26 ERA … 2.47 RA/9 … 1.09 WHIP … 25.7% SO rate … 82 batters per HR … .294 SLG
• After 105-114 pitches: 2.72 ERA … 2.88 RA/9 … 1.09 WHIP … 25.1% SO rate … 64 batters per HR … .317 SLG
• After 115-132 pitches: 3.86 ERA … 4.14 RA/9 … 1.11 WHIP … 24.5% SO rate … 40 batters per HR … .360 SLG

The extra-base hits rate progressed from 27% to 31% to 36%. For each group of starts, the average days’ rest was between 4.4 and 4.5.

This study is quick and dirty, but it tends to suggest that Kershaw is more vulnerable to the long ball after a high-pitch start, even with normal rest. And what does the Braves’ lineup do best?