MLB Daily DeltaWeek 27 · September 30, 2026
week 27
this weekHOLD
last week—

Sean Sullivan

COL·P
data as of September 30, 2026·week 27
Hold · wait & see strikeout rate 14% is stable and well below league, limits the ceiling — BABIP-against 0.367 elevated and unstable, the 8.87 ERA overstates the damage; but luck-free xERA 4.82 is +0.72 vs league, the level it regresses to is below average, not a buy; hold and wait — key skill metric not yet stable enough to call.med 0.55
ROSK 0ERA 4.10WHIP 1.30W 0–0SV 0

Sullivan is a hold — his ERA is misleading, but so is any buy case.

His ERA is 8.87, and that number overstates the damage. His BABIP-against is .367 against a league average of .295, and BABIP-against needs around 800 balls in play to be reliable — he has 84. That gap is luck, not skill, and it is why his expected ERA is 4.82, nearly four runs lower than his surface line. But 4.82 is .72 above the league average of 4.10, so the level he regresses to is below average. He strikes out just 14% of batters, well below the 22% league average, and his 87.6 mph fastball is over six mph below league. The panic is louder than the problem, but there is no upside here either. Hold. 0 K and a 4.10 ERA ROS makes this a drop — waiver-wire filler with no strikeout path to relevance.

Drivers

  • babip_againstNOISEBABIP-against 0.367 elevated and unstable — the 8.87 ERA overstates the damage
  • xeraNOISEbut luck-free xERA 4.82 is +0.72 vs league — the level it regresses to is below average, not a buy
  • p_k_pctSIGNALstrikeout rate 14% is stable and well below league — limits the ceiling
metric · nowrolling trajectoryvs. leaguestabilized?
Hard-Hit % Allowed34.5%
34.5%*
lg avg 40.0% ▼−5.5%vs his norm —
84 / 50 BBE
Barrel % Allowed9.5%
9.5%*
lg avg 8.0% ▲+1.5%vs his norm —
84 / 60 BBE
xwOBA Allowed.335
.335*
lg avg .315 ▲+.020vs his norm —xwOBA Allowed is above the ~.315 league average — expect it to fall.
114 / 200 TBF
xERA4.82
4.82*
lg avg 4.10 ▲+0.72vs his norm —xERA is above the ~4.10 league average — expect it to fall.
114 / 200 TBF
ERA8.87
8.87*
lg avg 4.10 ▲+4.77vs his norm —ERA is above the ~4.10 league average — expect it to fall.
22.3 / 200 IP
Strikeout %14.0%
14.0%*
lg avg 22.0% ▼−8.0%vs his norm —
114 / 70 TBF
Walk %9.6%
9.6%*
lg avg 8.0% ▲+1.6%vs his norm —Walk % is above the ~8.0% league average — expect it to fall.
114 / 170 TBF
BABIP Against.367
.367*
lg avg .295 ▲+.072vs his norm —BABIP Against is above the ~.295 league average — expect it to fall.
84 / 800 BIP
Swinging-Strike %7.7%
7.7%*
lg avg 11.0% ▼−3.3%vs his norm —
114 / 60 TBF
Chase %28.1%
28.1%*
lg avg 28.5% ▼−0.4%vs his norm —
114 / 60 TBF
Fastball Velo87.6 mph
87.6 mph*
lg avg 94.0 mph ▼−6.4 mphvs his norm —
412 / 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% 14.0%→15.6%signal0 K — K% 14.0% (signal) lifted to SP mean ~22.0% → projected 15.6% over ~0 remaining IP.
xERA 4.82noise4.10 ERA — xERA 4.82 (noise) blended 0% skill / 100% league 4.10 at 3 IP.
BB% 9.6% + contactnoise1.30 WHIP — a 10% walk rate plus BABIP-against 0.303 gives a 1.60 skill WHIP, blended 0…
run support + role0-0 W — wins ride run support and how deep he goes, not just skill.
role (starter)0 SV — role: starter, not in the save mix.
rosterdrop0 K ROS, 4.10 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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