Bert Blyleven vs Jerry Koosman: Career Stats Comparison
Bert Blyleven (1970–1992) and Jerry Koosman (1967–1985) — breaking in during the 1970s and the 1960s respectively, so they pitched against very different hitting environments. Bert Blyleven compiled 287 wins and 3,701 strikeouts; Jerry Koosman put up 222 wins and 2,556 strikeouts. The numbers below run them through identical career and rate-stat lenses.
Bert Blyleven
Jerry Koosman
Career Stats Side-by-Side
Every cell below is a career total or career rate. Cells highlighted in green mark the player who leads that line. For pitchers, lower ERA, WHIP, and BB/9 lead; higher K/9 leads.
| Statistic | Bert Blyleven | Jerry Koosman |
|---|---|---|
| Wins | 287 | 222 |
| Losses | 250 | 209 |
| Games | 692 | 612 |
| Games Started | 685 | 527 |
| Complete Games | 242 | 140 |
| Shutouts | 60 | 33 |
| Saves | 0 | 17 |
| Strikeouts | 3,701 | 2,556 |
| Walks | 1,322 | 1,198 |
| Hits Allowed | 4,632 | 3,635 |
| Home Runs Allowed | 430 | 290 |
| Innings Pitched | 4,970 | 3,839 |
| ERA | 3.31 | 3.36 |
| WHIP | 1.20 | 1.26 |
| K/9 | 6.70 | 5.99 |
| BB/9 | 2.39 | 2.81 |
PIV Comparison
By PIV (Player Impact Value), Bert Blyleven outpaces Jerry Koosman 74,910 to 42,939 — a gap driven primarily by per-season impact (3,121 vs 2,147 per year). PIV adjusts each season to league baselines, so it's the cleanest way to compare careers across eras.
Peak Seasons
The best single seasons each player produced, ranked by ERA among qualified workloads (120+ innings).
Bert Blyleven — top 3 seasons by ERA (lower is better)
Jerry Koosman — top 3 seasons by ERA (lower is better)
Verdict
On the head-to-head card, Bert Blyleven leads in wins, strikeouts, ERA, and WHIP, while Jerry Koosman owns no headline categories. That doesn't settle the era debate, but on the raw scoreboard the edge goes to Bert Blyleven. PIV agrees: Bert Blyleven grades out higher across their careers. Click through to each profile for the full season-by-season breakdown.