Joe Nathan has had Tommy John surgery before. Joe Nathan will need to have Tommy John surgery again. He has proclaimed that he intends to come try to return, but the odds are against that — 41-year-old major league pitchers are in short supply (there are just two this season). Whether he does or doesn’t make it all the way back, any subsequent seasons are unlikely to add much to his statistical ledger. And an impressive ledger it is.

A sixth-round pick in the 1995 draft, Nathan has been one of the few players left in the game who saw action back in the 90s, as he debuted for the Giants back in April of 1999. He was a starter back then, though he wasn’t particularly good. He only struck out three more batters than he walked in those 14 debut season starts. He would get another crack at starting the next season, but in his 15 starts in 2000 he struck out four fewer batters than he walked, and that was the end of that chapter.

Well, sort of. He would be a starter for the bulk of the next two seasons, at age 26 and 27, but he would do so in the minor leagues. His 2001 was an unmitigated disaster — he struck out 54 against 70 walks in Double-A and Triple-A — he walked more guys than he struck out at both levels. He was better in 2002 — 117 Ks against 74 walks, all at Triple-A Fresno — but he allowed 20 homers, had a 1.647 WHIP and 5.60 ERA. Better, but not good. He would come back up to San Fran in September for four scoreless relief appearances, and never looked back.

When I remember the A.J. Pierzynski trade, I generally think of him as being dealt for three guys who had a lot of promise but hadn’t really accomplished anything quite yet. And in the case of Boof Bonser and Francisco Liriano that is certainly true — neither would debut in the majors for another couple of seasons. Nathan, on the other hand, was pretty good in relief in 2003. Not so good that you could say the Twins saw his breakout coming, but he was pretty good. His 1.38 WPA ranked 43rd among relievers, and his +17 shutdowns minus meltdowns mark tied for 23rd-best.

Fast forward 12 seasons, and Nathan currently finds himself seventh all-time in saves. That’s going to lead to a lot of talk about Nathan as a Hall of Famer. Let’s take a look at that top 15 in saves.

Statistical Comparison, Top 15 Career Saves Leaders

Looking at this table, the thing that sticks out the most is just how much Nathan made of his opportunity. He has comparatively few innings pitched, and yet finds himself in the top five in RE24 and the top three in WPA. He doesn’t quite get to the top five in WAR, but then WAR isn’t necessarily the best tool for judging relievers anyway. As a result of his lack of time relative to the others, he has the second-fewest meltdowns, and Jonathan Papelbon will probably slide past Nathan eventually. As a result, he ranks sixth in shutdowns minus meltdowns. Nathan has given up his share of home runs and walks, but he also struck out more batters than most of his closer ilk.

And it’s not just compared to other closers that Nathan’s rate stats look good. Among the 344 relief pitchers who have tossed at least 500 relief innings (since 1916, which is the first season for which we have K% and BB%), Nathan’s 20.8% K-BB% is tied for third with Dennis Eckersley, and the two of them are just two of six who are at 20 percent or higher.

What sticks out even more is how he stacks up in terms of WPA. Among all relief pitchers, he ranks fourth — behind just Mariano Rivera, Trevor Hoffman and Rich Gossage. Now, Gossage pitched for two seasons before the first season we have WPA data for (1974), but given his cumulative -0.3 WAR and 5.48 ERA from those two seasons, they probably wouldn’t have added a lot to his WPA total. When you factor in starting pitchers, whom WPA isn’t always kind to, Nathan drops back to 15th. Still pretty damn good. Either way, being in the same class with Rivera (sure-fire Hall of Famer), Hoffman (probable Hall of Famer) and Gossage (actual Hall of Famer) is going to look good on Nathan’s resume.

What won’t look good, of course, is his postseason work. Nathan pitched 10 postseason innings, seeing action with each of the four teams for whom he has pitched, and allowed nine runs. He has struck out 12 and walked eight, and has allowed more home runs (two) than he has saved postseason games (one). Both of those homers got Nathan charged with a blown save, but while the first one was in the sixth inning in 2003 when Nathan was still a pup and could be hand waived, the second one is a little harder to justify:

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(Note all the cheering for Alex Rodriguez. He even got a curtain call.)

The Twins would hold the lead for a solitary half-inning after Nathan allowed this homer. This series would mark the third straight time the Yankees had beaten the Twins in the postseason, and they would make it four in a row the following season, though Nathan would sit that out, as he was recovering from his first Tommy John surgery. If not for this homer, you could kind of squint at his postseason line and discount some of it for being early career, but in 2009 (and in 2012, when he didn’t help matters in the Wild Card game) he was pretty damn good. Of course, you could also make the case that Nathan was hurt even then, and that the 2009 series should be discounted as well, but that’s kind of a tough sell. Of course, it’s also just 10 innings, and we shouldn’t put too much stock in it. But it would have been helpful to his case if they were 10 good innings, at least.

When he was a closer, there were few better than Joe Nathan. In fact, you could say just one — Mariano Rivera. From 2004 (when Nathan began closing) to 2013 (the end of Rivera’s career), only Rivera saved more games or had a better WPA.

If you’re a fan of sabermetrics, Joe Nathan’s Hall of Fame candidacy likely comes down to how you want to frame the discussion. If you look at his 19.4 career WAR and deem that too low and shut it down right there, well you probably won’t be alone. And probably aren’t wrong. But if you look at some other metrics, like WPA, and K-BB%, and take a look at how he compared to his peers in his era, a case begins to form. It might not be any better than the cases that Lee Smith or Jeff Reardon or a half dozen other guys could make, but there’s a case to be made nonetheless. And the fact that there is a case to be made just goes to show how great of a career Nathan had.