White Sox bullpen still counting on Zach Putnam

By spending $61 million on David Robertson and Zach Duke, Rick Hahn decided to solve the White Sox's relief crisis with blunt force.

We'll know who the closer is in 2015. We'll also know the primary lefty, and the Sox have a group of candidates for the usually interchangeable second-lefty position.

Now, the biggest question regarding the bullpen is, "Who's the second-best righty?"

By 2014 performance, it's Zach Putnam. He led White Sox relievers in ERA (1.96) over 49 games, allowed just two homers, and showed an ability to retire both righties and lefties. That gives him an edge over Petricka, who was vulnerable to lefties, and ended up yielding some of those match-ups to Putnam later in the season.

It's quite remarkable that Putnam pitched in so many big situations during the second half, considering he started the season as a non-roster invitee. The destruction and despair around him made it possible, but hey, if a puppy wants a home, it has to climb on top of the other puppies to get out of the box.

The out-of-nowhere results alone make Putnam the most intriguing out of the incumbents, but it's hard to count on a repeat of such a stalwart performance due to a couple of extreme underlying factors.

Putnam is kinda the right-handed version of Duke, in that he put together an excellent year out of the bullpen when nobody expected it, simply because something clicked. In Duke's case, he started throwing more breaking balls than fastballs, and from two different arm slots.

In Putnam's case, he relied heavily on his splitter. Steve pointed out the emergence of the pitch with Putnam and other Sox relievers back in June, and just to revisit it that point with a full season's worth of data, he used it more than any pitcher in baseball last year:

1. Zach Putnam, 56.4 percent
2. Jean Machi, 49.0 percent
3. Koji Uehara, 47.6 percent

And hell, clicking back through single seasons in FanGraphs, Putnam threw splitters at the highest frequency of any qualifying reliever in the PITCH f/x era (2002-present), with only Edward Mujica reaching the 56 percent mark at any point.

The heavy reliance on the splitter was a long time coming, according to John Sickels, who filed this report on Putnam in 2009:

The Indians spent $600,000 to sign him, well over slot, but very possibly worth the money. Putnam has a 90-95 MPH sinking fastball, and a diverse arsenal of secondary pitches including a curveball, slider, splitter and changeup. Indeed, some scouts believe that he throws too many pitches and would be better off picking two of them to focus on in addition to the fastball; probably the splitter and slider.

Sure enough, Brooks Baseball says he threw fastballs just 17 percent of the time in 2014, down from 55 percent over his first three cups of coffee.

This is a valid reason to believe in Putnam's prospects going forward. Not to compare every darn reliever to Jesse Crain, but there's something to be said for throwing your best pitch instead of your worst pitch, even if it results in a highly unconventional mix.

But it might be hard to match his performance when it comes to limiting runs -- and I'm not just talking about the flags that pop up on the standard Jiffy Lube 14-point sustainability check (ERA against his strikeout rate, BABIP, home runs per fly ball, etc.).

While Putnam ended up on the good side of just about every contact-related pitching measure, here's the stat that sticks out to me: Putnam stranded 26 of 29 inherited runners in 2014.

Some so-so relievers can post impressive ERAs  because their damage comes at the expense of the reliever who preceded them, but Putnam posted a 1.96 ERA for himself, and did what he could to improve his colleagues' stats, too.

(Javy Guerra is the Goofus to Putnam's Gallant, posting a 2.91 ERA, but allowing a whopping 15 of 29 inherited runners to score.)

There really isn't a strong base line for stranding inherited runners, but Baseball-Reference.com's Play Index helps contextualize this achievement. I searched for the lowest strand rates of pitchers who inherited at least 25 runners (Putnam had 29) while throwing 50 innings (he threw 54⅔). The latter criterion helps filter out the LOOGYs, who aren't really comparable to Putnam in this situation.

Here are the pitchers who stranded at least 89 percent of his inherited baserunners in 2014:

1. Jake McGee (27 of 30)
   
2. Zach Putnam (26 of 29)
   

That's it. Crazier still, using the same parameters, here's the list of White Sox pitchers who stranded at least 89 percent of his inherited baserunners since 1990.

1. Zach Putnam (26 of 29)

Yeeeeep. Matt Thornton comes the closest, going 27-for-31 (87 percent) during his excellent 2010 season.

This is pretty ... something. That word might be "random" if he were a garden-variety second lefty, because this happens to LOOGYs pretty frequently. Just in the last three years:

• Donnie Veal, 2012 (21 of 23)
• Eric Surkamp, 2014 (25 of 28)
• Scott Downs, 2014 (24 of 28)

It's strange to see Downs on that list, but LOOGYs are deployed for favorable situations, and they don't ever have to see the inning all the way through for the runner to count.

Putnam, on the other hand, both worked full innings and against his platoon split. He faced more lefties than righties in 2014 -- partially because of late-inning pinch-hitters, but also because he was the best option Ventura had against lefties.

In the end, it's still more random than it is meaningful -- it just happens to be random against far more staggering odds, so it seems like it deserves a better tag than "meh, luck." Plus, if it's pure chance, that leaves open the possibility of regression being equally severe. I suppose everybody's going to have to trust the splitter on this one.