MLB Daily DeltaWeek 31 · October 26, 2026
Engraved portrait of Aroldis Chapman
week 31
this weekBUY
last weekNO CALL

Aroldis Chapman

BOS·P
data as of October 26, 2026·week 31
new call as of October 26, 2026
Buy stable xERA 2.64, 1.46 below league, production is earned; velocity stable and above league; add now.high 0.92
ROSK 0ERA 2.64WHIP 1.25W 0–0SV 0–0

Chapman is a buy — the 2.64 expected ERA is earned, not lucky.

His expected ERA is 2.64 — a run and a half below the league average of 4.10 — and he has faced the 200 batters it takes for that number to become reliable. The expected ERA has stepped down across the sample, and the fastball has stepped up: 96.9 mph, nearly three mph above league, on a stable pitch sample. What makes the run prevention real rather than a streak is where it comes from. He strikes out 33.3% of batters, well above the 22% league rate, and his swinging-strike rate is 15.8% against 11%. His expected wOBA allowed of .252 runs well under the .315 league mark. The walk rate is 10.8%, a little high, so the bases get occupied — the trade-off is real but it does not move the call. This is earned run prevention. Buy. 0 SV at 2.64 ERA and 1.25 WHIP is a ratio asset, not a saves source — add now for the ratios, not the category.

VS His Norm

  • Strikeout %33.3%—−6.4% ▼vs his ~39.7% career norm
  • Walk %10.8%—−1.4% ▼vs his ~12.2% career norm

Drivers

  • xeraSIGNALstable xERA 2.64, 1.46 below league — production is earned
  • p_fastball_veloSIGNALvelocity stable and above league
metric · nowrolling trajectoryvs. leaguestabilized?
Hard-Hit % Allowed38.1%
believable since Jun 2338.1%*
lg avg 40.0% ▼−1.9%vs his norm —
118 / 50 BBE
Barrel % Allowed6.8%
6.8%*
lg avg 8.0% ▼−1.2%vs his norm —
118 / 60 BBE
xwOBA Allowed.252
.252*
lg avg .315 ▼−.063vs his norm —
213 / 200 TBF
xERA2.64
2.64*
lg avg 4.10 ▼−1.46vs his norm —
213 / 200 TBF
ERA1.92
1.92*
lg avg 4.10 ▼−2.18vs his norm —ERA is below the ~4.10 league average — expect it to rise.
51.7 / 200 IP
Strikeout %33.3%
norm33.3%*
lg avg 22.0% ▲+11.3%vs his norm −6.4% ▼
213 / 70 TBF
Walk %10.8%
norm10.8%*
lg avg 8.0% ▲+2.8%vs his norm −1.4% ▼
213 / 170 TBF
BABIP Against.283
.283*
lg avg .295 ▼−.012vs his norm —BABIP Against is below the ~.295 league average — expect it to rise.
118 / 800 BIP
Swinging-Strike %15.8%
15.8%*
lg avg 11.0% ▲+4.8%vs his norm —
213 / 60 TBF
Chase %33.1%
33.1%*
lg avg 28.5% ▲+4.6%vs his norm —
213 / 60 TBF
Fastball Velo96.9 mph
96.9 mph*
lg avg 94.0 mph ▲+2.9 mphvs his norm —
841 / 50 PITCHES

5×5 ROS Outlook

rest of season

Where each category goes the rest of the way, and the skill that drives it. Tap a row to expand the full derivation.

statytdrosdriverconf
K% 33.3%→36.4%signal0 K — K% 33.3% (signal) lifted to career ~39.7% → projected 36.4% over ~0 remaining IP.
xERA 2.64signal2.64 ERA — regresses up toward xERA 2.64 (signal): elite skill, but overperforming even…
BB% 10.8% + contactsignal1.25 WHIP — a 11% walk rate plus BABIP-against 0.293 gives a 1.25 skill WHIP, blended 6…
run support + role0-0 W — wins ride run support and how deep he goes, not just skill.
role (closer)0-0 SV — role: closer.
rosterstandard12 SV, 2.64 ERA

Every projection traces to a sabermetric input. The driver and confidence shown per row are always visible; tap any row to expand the full derivation.

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