Felix Hernandez is approaching the 2000 inning milestone. Barring injury, he should get there this season. If he does, he will be just the 21st pitcher of the live ball era to reach that milestone in his age 28 season or younger.

But, what does that portend for the remainder of his career? I’ll consider that question after the jump.

If Hernandez does reach 2000 innings this season, he will be the first to do so aged 28 or younger since Dwight Gooden in 1993, and only the third to do so since 1980. Here’s the list:

As shown, all of these pitchers compiled at least 20 WAR over the period, including four over 50 WAR and four more over 40 WAR. Their innings track fairly closely to their WAR in that only one of the six with fewer than 2100 IP compiled more than 30 WAR (Dierker), and only two of the others compiled less than 30 WAR (Coleman, Hunter). Four of the 20 pitched over 2450 innings, about two seasons worth of innings above the threshold. The median ERA+ of the group is 118, with 6 of the 20 posting a result better than 125.

Where will Hernandez fit in this group? Felix will be under 2100 innings and will be the first of those under that threshold to compile 40 WAR. His WAR rate of better than 2 WAR per 100 IP puts him in the company of Blyleven, Newhouser, Roberts, Feller, Ferrell and McDowell (4 out of 6 HOFers is a pretty good ratio). Hernandez’s ERA+ will most likely be above 125, joining Drysdale and (again) Ferrell, Blyleven, Roberts, Feller and Newhouser.

How did our group do after age 28?

Not unexpectedly, less impressive results with just three (and almost a fourth) of the 20 compiling 30 WAR (not coincidentally the same four who compiled another 2000 IP), and half of the 20 registering 10 WAR or less. The median IP is just over 1000 IP, which is perhaps surprisingly low given the durability this group displayed in getting to 2000 IP. Of the elite 5 who posted the best under-29 WAR Rate and ERA+, Blyleven and Roberts had long and successful second halves, Feller had a few more good seasons (but only good), and Newhouser and Ferrell were mostly done, each with only about 500 IP left.

So, will Hernandez be another Blyleven or Roberts. Or, is Newhouser or Ferrell the more likely outcome? As with all recent pitchers, Hernandez has had his workload closely managed, with no seasons of 250 IP (Felix was one out short of that mark in 2010). Everyone in the comparison group has at least one such season by age 28, with a median of 5 seasons. Of the 8 pitchers with 6 seasons or more, all had at least 500 more IP and 5 had more than 1000 IP, including two with over 2000 IP after age 28. Looking at the 8 pitchers with 4 seasons or fewer of 250 IP, three had less than 500 IP left and four had more than 1000, including one with over 2000 IP remaining. So, not obvious from this group that fewer high-inning seasons increased career longevity.

Another factor to consider is “stressful” innings of which Hernandez, owing to Seattle’s mostly anemic offenses, is said to have had more than his fair share. The numbers bear out that surmise with Hernandez logging 144 starts of 7+ IP allowing 3 runs or less, trailing only the leading total of 145 since 2005 by C.C. Sabathia. Hernandez similarly trails by only one the leading mark of 61 by Matt Cain, of such games that the starter did *not* win. Hard to compare a stat like that with pitchers in earlier eras but, for what it’s worth, Hernandez’s 58.3% of such games won is lower than every one of our group of 20, and his 21.4% of all starts that are represented by such games *not* won is similarly higher than every one of our group. Both of those results indicate a pitcher who, despite pitching well, is often pitching in close games with correspondingly higher stress levels in later innings.

What might be most concerning for Seattle, though, is Hernandez’s peak. His two seasons of 6 WAR and 170 ERA+ came at age 23-24. Since then, he’s averaged 4.5 WAR and 118 ERA+. Eleven of the 20 pitchers in our group had a qualifying 140 ERA+ season by age 24, including Mel Harder, the only one like Hernandez to have two such seasons by then. Of those eleven, only Blyleven and Feller recorded 1500 IP after age 28, with 7 of the other 9 below 1000 IP, including three with less than 500 IP. Of those eleven, only Blyleven had a 5 WAR season after age 28 (Bert had four of those), with six failing to record even one season of 4 WAR.