Quality sixth starters

When the Cardinals lost Adam Wainwright, they didn’t just lose a reliable Cy Young contender, they were confronted with the challenge almost every team has had to overcome, every year, going back to forever: How do you replace a rotation regular? As it turned out, they had a ready alternative in Kyle McClellan, who became the National League’s first six-game winner on Thursday.

At first blush, McClellan’s breakthrough is a straightforward reminder that teams can find useful starting pitchers in the bullpen; the Rangers fished C.J. Wilson out of relief before their pennant-winning 2010 season, after all. But wherever a sixth starter comes from, the larger point is that there isn’t a team in baseball that doesn’t need him. Going back to 1901, just five teams have managed to get through a full season while using five starting pitchers, and three of those clubs played in the first few years during the Deadball Era, when workloads, pitching schedules and offensive levels were very different. Only two ballclubs -- the 1966 Dodgers, and the 2003 Mariners -- have managed the feat of using five starters in the 162-game season. Even then, the Dodgers may not have had the dead ball, but future Hall of Famers Sandy Koufax, Don Sutton and Don Drysdale had the benefit of the high mound, which helped scoring plummet during offense’s little ice age.

That’s the sort of information that ought to depress anybody who might be wondering whether his or her team’s rotation will make it through a full season. No matter how carefully a staff’s workload is managed, even in today’s pitch-count-conscious era, as a group any front five isn’t going to make it through a season without something going awry. Somebody’s going to break down, need additional rest or deserve to be bumped for plain old ineffectiveness.

As a result, any well-run franchise has to lay in reserves if it wants to keep its rotation in working order. With that in mind, beyond McClellan, which sixth men have already had to be plugged in, and have answered the call? Using WAR as a quick way to rank the best starters who have had to step into someone else’s slot, and SIERA to tell us which way their ERAs are probably headed, here’s a rotation’s worth of the best replacements:


* Values not updated through Thursday's action, but I will once those numbers are published.

Zach Britton, Orioles: Britton’s hardly your classic sixth man since the power lefty came into the season as the O’s top pitching prospect. That’s the virtue of an Orioles system stuffed with pitching talent, as Britton’s anticipated arrival inspired Jeremy Guthrie trade rumors. However long it took until Britton was ready, former prospects like Jake Arrieta, Chris Tillman and Brad Bergesen were going to be pitching for their jobs in the meantime, even after Justin Duchscherer’s regularly scheduled debilitating hip injury. However, after Brian Matusz’s spring training back injury created one more open slot for Britton, the Arrieta/Tillman/Bergesen trio is now locked into a battle to determine who will become the depth chart’s sixth starter du jour, because Britton’s trip up the totem pole looks strictly one way.

Alexi Ogando, Rangers: Calling Ogando even the team’s sixth starter might be a bit generous in terms of his ranking on the depth chart, because between Brandon Webb’s super slo-mo comeback, Neftali Feliz’s job-title drama and Tommy Hunter’s spring injury, even then he was behind lefty Matt Harrison in the queue to get a starting gig. However, between showing improved touch on his slider to neutralize lefties and a four-seam fastball hitters swing through, Ogando has rattled off seven quality starts in eight. Now it looks like he won’t be anyone’s sixth man again any time soon. Harrison has been fine in his slot as well (6-for-8 in quality starts), putting the Rangers in the happy position of being able to take their time with Webb and Hunter while guaranteeing that Feliz’s future will continue to be as the club’s designated saves-generator.

Tyson Ross, Athletics: With Dallas Braden done for the year after surgery on a torn capsule, the A’s ambitions for AL West contention had to fall on somebody else’s shoulder -- it turned out to belong to Ross, a hard-throwing Cal product who spent much of last year in a mop-up middle-innings role. Unfortunately, he left Thursday’s game with a strained oblique, so we’ll see who may have to come out from behind door No. 7 for Oakland.

Philip Humber, White Sox: If anyone might seem like a classic example of a fifth-slot aspirant, it might be Humber, a strike-throwing finesse righty in a world that generally doesn’t show them a lot of love. Hop-scotching from the Royals to the A’s to the White Sox via waivers, he was plugged in as a well-traveled temp once Jake Peavy’s ambitious Cactus League campaign to come back was stopped short. Humber has subsequently served notice that he can mix pitches effectively enough to be kept around, as Ozzie Guillen has decided to run with a six-man rotation for the remainder of the month now that Peavy’s back.

Looking at the group, McClellan ranks among but not clearly atop this quintet, and the direction that his SIERA suggests his ERA will be headed is far from promising. Then again, if his performance in the peripheral data -- the information that reflects dominance -- had been great in the first place, he probably wouldn't have been a sixth man. Perhaps what's especially important so far is that McClellan has been durable, and health is a valuable skill, one that Ross might already envy.

And what group of five starting pitchers would be complete without a sixth man ready to potentially step in? My pick would be the Twins’ Kevin Slowey, who only finds himself in the extra man’s predicament because of the Twins’ faith in Nick Blackburn and Brian Duensing, despite Slowey’s stronger recent performance in a rotation and stronger projections (3.93 via PECOTA, 4.33 per ZiPS). But as any of these other former sixth men might be able to say, tomorrow’s opportunity can be found on the other side of today -- and perhaps someone else’s misfortune.

Christina Kahrl covers baseball for ESPN.com. You can follow her on Twitter.