Designated HitterDecember 14, 2005
Bert and Warren: A Comparison Worth Making
By Dayn Perry

Over at the inestimable, if you level your gaze at Bert Blyleven's list of top ten most similar pitchers, here's what you'll find (with precise similarity scores in parentheses):

 1. Don Sutton (914)
 2. Gaylord Perry (909)
 3. Fergie Jenkins (890)
 4. Tommy John (889)
 5. Robin Roberts (876)
 6. Tom Seaver (864)
 7. Jim Kaat (854)
 8. Early Wynn (844)
 9. Phil Niekro (844)
10. Steve Carlton (840)

As you can see, peppering Blyleven's particular litany are eight Hall of Famers (Tommy John and Jim Kaat being the only exceptions). Suffice it to say, those are some impressive fellow travelers. However, one player not on Blyleven's list of similars who perhaps should be is Warren Spahn--the winningest left-hander in the annals of the game.

Superficially, there's not much linking these two. Spahn was a port-sider who relied on his heater until a knee injury forced him to develop a screwball, which became his out pitch over the latter half of his career. He retired following the 1965 season. The right-handed Blyleven, meanwhile, was a curveball specialist who pitched into the 1990s. More to the point, Spahn was voted in to the Hall of Fame in his first year of eligibility, and Blyleven was named by only 40.9 percent of voters in his eighth year on the ballot. They were different pitchers in different eras with different styles and, bizarrely enough, divergent reputations. Still and yet, these two hurlers share remarkably similar statistical profiles--provided you look at the right numbers.

You won't find Spahn on the list above because similarity scores, for the most part, rely on rank-and-file measures like wins, losses, winning percentage, unadjusted ERA, games pitched, innings, hits allowed, etc. However, if we rely on the more evocative pitching metrics, we find the two hurlers to be cut from an almost identical cloth. Consider these career comparisons:

                            Blyleven	          Spahn
Innings                      4,970.0          5,243.2
ERA+                           118              118
H/9 vs. League Avg.             95               93
K/9 vs. League Avg.            128               95
BB/9 vs. League Avg.            73               73
HR/9 vs. League Avg.            97               87

This table shows us that Spahn bested Blyleven in innings (narrowly considering the length of their careers), league-adjusted H/9 (narrowly again), league-adjusted HR/9 (semi-comfortably, although considering all the hand wringing over Blyleven's homer proclivities, it might surprise some to see that he was better than the league mean in this regard), while Blyleven was superior in league-adjusted K/9 (by a country mile or so). The two pitchers were roughly equal in park- and league-adjusted ERA and in league-adjusted BB/9. Considering the gaping divide between their fates--Spahn a pantheon-dwelling treasure, Blyleven forced to dither unjustly on the margins of very-goodness--you'd expect more of a statistical disconnect. Yet there's no such thing.

The difference, of course, is wins--the hoary, useless measure of pitching performance that's obsessed those of mainstream inclinations since the days of the trilobites. Spahn has 363 of them, good for sixth place on the all-time list, while Blyleven ranks "only" 25th with 287. There's a reason for this, and it's probably a patently obvious one to regular readers of a site as heady as this one: run support.

By using "neutral wins" (NW) and "neutral losses" (NL) we can assess what a pitcher's record would've been had he been graced (or burdened, as the case may be), over the same number of decisions, with league-average run support. Thanks to the efforts of Lee Sinins and his straight-from-heaven Sabermetric Encyclopedia, we have the career NW and NL numbers for Blyleven and Spahn:

                         Blyleven	              Spahn
Actual W-L record        287-250 (.534)	     363-245 (.597)
Neutral W-L record       313-224 (.583)	     353-255 (.581)

Without correcting for run support, Spahn quite famously has a comfortable advantage in winning percentage; however, if you recalibrate for Blyleven's generally lousy lineup compatriots, he actually outdoes Spahn in such a neutral context. At this juncture two points bear repeating: Blyleven is the equal of Spahn--the board-certified, inner-circle Hall of Famer--in terms of park- and league-adjusted ERA, and he bests him in winning percentage once league-average run support is ascribed to both hurlers. Why there's any sort of debate over Blyleven's Cooperstown bona fides is truly a mystery. But let's carry on . . .

It's no longer elusive knowledge that ERA is a sub-optimal way to evaluate pitchers. ERA and, by extension, earned and unearned runs aren't as laughably bootless as, say, RBI or the previously sullied pitcher wins and losses, but they're still fraught with inadequacies. Those shortcomings likely don't need rehashing with this audience, so let's leave it at this: runs-per-game is a better performance measure. That's mostly because runs-per-game (R/G) leaves out the inanities involved in scoring errors and isn't soiled by the overly forgiving nature of the unearned run rule.

                            Blyleven           Spahn
Career R/G                    3.67	           3.46
Career R/G vs. Lg. Avg.        90                80 

This is a fairly clear advantage for Spahn. Both were comfortably better than the league average, but Spahn betters Blyleven by ten percent in league-adjusted R/G, which reflects the fact that Spahn, generally speaking, pitched in a more offensive environment. Of course, there's also the matter of park effects.

While park tendencies are reflected in ERA+, they're not in the other semi-sophisticated measures you'll find above, including league-adjusted R/G. Insofar as this particular comparison is concerned, it's vital that we explore the parks these two toiled in for their careers. Summarily speaking, Blyleven had a substantially tougher go of it. For his career, Blyleven's home parks had an average factor of 102.0, and in only two seasons did he pitch in a ballpark that favored the pitcher. In stark contrast, Spahn's home parks had an average factor of 94.5, which indicates, on balance, a strong tendency toward run suppression, and in all but three of his 21 full seasons in the majors his parks favored the pitcher. That's a healthy dose of disparity in terms of environment, and it's not reflected in many of the measures we've dealt with heretofore. So let's recast R/G after correcting for league and home digs:

                                   Blyleven       Spahn
Park-adjusted R/G                    3.63          3.56
Park-adjusted R/G vs. Lg. Avg.        89            82

Spahn still holds sway after adjusting for the foibles of home park, but the gap narrows.

Overall, Spahn worked more innings and was better at keeping the ball in the park (although that was partially by dint of his home environments) and keeping unearned runs off the board. Blyleven, on the other hand, had superior strikeout chops and fared better once run support is made part of the calculus. Blyleven also tops Spahn in career Runs Saved Above Average, 344 (17th all-time) to 319 (20th all-time).

Spahn, of course, deserves qualitative bonus points for losing up to three years of his career to military service during World War II, and he was also a better hitter and fielder than Blyleven. In the final statistical analysis, Spahn cobbled together the better career, but that there's even been a protracted discussion on the subject--who's better, Spahn or Blyleven--is telling and to Blyleven's tremendous credit.

Put another way, to suggest that Blyleven isn't a Hall of Famer is also to suggest that the quality of Spahn's Cooperstown dossier is at least contestable. Who out there is willing to say that?

Elect Bert Blyleven to the Baseball Hall of Fame.

Dayn Perry is a baseball writer for and an occasional contributor to Baseball Prospectus. His forthcoming book Winners: How Good Baseball Teams Become Great Ones is available for pre-order from

[Additional reader comments and retorts at Baseball Primer.]


What a great, fresh piece. The only good thing about Blyleven not yet in the Hall is knowing there will be great articles surrounding his glaring omission.

Remind me again why guys like Neyer and Perry aren't voters for the Hall?

I grew up watching Bert pitch, albeit on TV, and while I am not sure he is HOF material, I love your arguments-as a kid, my friends and I never thought him to be in the class of Seaver, Carlton, Hunter, Guidry etc- but much of that was perception based on TV time, Media and playoff/WS exposure-as far as HOF voting etc, how is it possible that there has NEVER been a unanimous vote for entrance-Mays, Aaron, Bench, Brett,DiMaggio, Williams, Seaver- how is none of THESE unanimous?? Love your site and articles.

Great article. Spahn and Blyleven enjoyed similar types of careers -- ones that lasted a very long time and were marked by extreme durability. The only reason why everyone says Spahn was so great (not to suggest he wasn't) is because he happened to finish up with more wins than any lefty in history. Blyleven gets completely ignored because he happened to finish 13 wins short of 300.

Spahn was a better pitcher, but the gap isn't nearly as wide as some would suggest.

Now this one I really like: kudos for developing a swell argument that, by aiming high rather than low, really succeeds in conveying just how great Blyleven really was. Sure, people can show that Blyleven is better than seeming-similars Kaat and John, or even HoFers Sutton, Hunter, and Jenkins, but none of those arguments resonate as strongly with "reg'lar folk" as saying, "Actually, let me tell you why inner-circle Warren Spahn (who you know and love) is only barely better than HoFer Blyleven, a clear HoFer". I think that this kind of an argument works because you're basically giving the reader a "f*** you" sucker punch by not even wasting time on the typical arguments because, OBVIOUSLY, those aren't even worth contesting. Like, "Dude, are you stupid or something - DUH, Blyleven's a Hall of Famer, it's only a question a how close he is to Lefty Grove. Stop wasting my time." You may not have realized that this is what you were saying, but, I assure you, it is.

All in all, pretty sweet. Nice work.

I used to love watching Warren Spahn pitch. Whenever Milwaukee came through Houston, he'd always figure out when Spahnie'd take the mound and we'd make that game. Spahn, Eddie Matthews, Hank Aaron, Del Crandall, what a lineup!

Your mention of lousy run support, especially in his early years with Minnesota, is right on. His highest ERA from 1971-1974 was 2.81, yet his team managed to help him to 66 losses over that span. As a Twins' fan from day one, I know Bert LOST a lot of 1-0 and 2-1 games in those first years with Minnesota. I don't know the exact figure but I'd bet that if he'd won half of them, he'd have his 300 wins and have been voted in already.

But of course, he deserves to be in, as well documented, regardless of his "failure" to win 300.