Junior Guerra and the Great Old Rookie Pitcher

Sometimes very talented position players stall on their way to the majors but stick around until they finally make good on their potential. Other times, slightly less talented position players keep slowly moving up the rungs of the minor-league ladder until they finally get their chance. This latter path marks the one traveled by Ryan Schimpf of the San Diego Padres, who is one of the better old rookies of the last half-century.

On the pitching side, however — especially where starters are concerned — the good old rookie is a more rare commodity. Junior Guerra is one such rookie, though, and the 31-year-old — off the disabled list tonight for the Milwaukee Brewers — is having one of the more remarkable pitching seasons in major-league history.

If you are a fan of either the Milwaukee Brewers or Carson Cistulli, you are likely familiar with Guerra. As to the former, Guerra has pitched very well this season, making 17 starts with a 2.93 ERA (68 ERA-), 3.65 FIP (84 FIP-), and 2.3 WAR on the season. As to the latter, regard:

• In early May 2015, after Guerra’s first 24.2 innings in an MLB organization in half a decade, Cistulli placed Guerra in his Fringe Five, noting that he had been signed by the White Sox out of the Italian league after having also pitched professionally in Spain and Wichita. (He’s pitched in Mexico, too, but after his release by the Mets in 2009, he went six seasons without pitching for an MLB organization).
• Just one day later, so entranced by Guerra’s profile, Cistulli furthered his study of the aging prospect in a post, showing off his mid-90s fastball and devastating splitter in helpful .gif form.
• That season, Guerra appeared not once, not twice, but three more times that year in the Fringe Five, making him one of the most prevalent players in Cistulli’s weekly exercise with his pace only slowed by four relief innings in the majors with the Chicago White Sox, who placed him on waivers at season’s end, when he was picked up by the Milwaukee Brewers.
• To nobody’s surprise, Cistulli then placed Guerra in his Fringe Five earlier this season, and when Guerra made his debut for Milwaukee, Cistulli called it a Jubilee Event.

All of which is to say, Guerra’s exploits were not necessarily on the radar of your more typical baseball fan. Guerra’s performance has been very good so far, and although he has been on the disabled list due to some elbow issues, which is always disconcerting, he is scheduled to return tonight.

In terms of older rookie pitchers this season, Guerra is in very good company. The table below shows rookie pitchers 27 years old or older who have registered at least 0.7 WAR this season.

The first two players on that list are technically rookies but have been pitching at a high level professionally for some time in Asia prior to pitching in the majors. After Maeda and Oh, it’s Guerra and a bunch of relievers. Few players have made a meaningful impact this season. Neris, like Guerra, is also known for his split-fingered fastball, and Matt Bush’s story is fairly well known. Beyond this list, only five other older rookie pitchers have received more than one start, and none of them (Joel De La Cruz, Pat Dean, Ariel Miranda, or Zachary Neal) are above replacement level this season.

What Guerra has done this season appears highly unusual, but we can take a broader approach to see how he rates historically. Prior to this season, over the last 50 years, only 46 pitchers had rookie seasons (not including those from Asia or Cuba) at age 27 or older and while recording at least (a) 10 starts and (b) 1.0 WAR. Of course, that sets the bar pretty low relative to what Guerra has done this season (17 starts, 2.4 WAR) and his age (31).

Let’s take a quick look at the slightly younger set of starting pitchers who have a WAR at least equaling Guerra’s 2.3 so far this season.

Some interesting names up there, although Bob Johnson and Mike Smithson might be the two most boring names you will see on a non-alphabetical chart back to back. Johnson never put up more than one win above replacement in parts of five major-league seasons, while Smithson had a few decent years with the Twins and also appeared on their Series-winning 1987 team before finishing up with the Red Sox after the 1989 season. Half the names are from the last decade with perhaps the most interesting player past that time period being the Brewers’ Steve Sparks, who took a while to get to the majors due to learning the knuckleball halfway through his minor-league journey.

As for older players like Guerra, there are very few of them who have ever done what he’s doing this year. Going back even further, since the end of World War II, here are the only players to record at least 1.0 WAR as rookies at least 30 years of age (not including recent additions from Asia and Cuba), with the stats below coming their starts (i.e. relief appearances are not included.)

Connie Marrero and Satchel Paige might not technically belong to this list given Paige’s lengthy career in the Negro Leagues and Marrero’s time in Cuba, but their debuts at their age were just too compelling to ignore. As for the rest, Papai is another knuckleballer and Ostrowski got a late start in his career, then served in the military. Keegan threw a no-hitter in 1957, at the time the second-oldest player to do so (Sal Maglie) and one of the few players to do so with only one strikeout, per Baseball Reference. In the last 50 years, only Chuck Smith and Pete Walker had rookie years even comparable to Guerra. Smith had one good year, followed it up with a lousy one and never made it back to the majors. Pete Walker actually made his major-league debut in 1995, and — along with 1996, 2000, and 2001 — he made 18 appearances before splitting 2002 between the bullpen and the rotation. He had a couple more seasons, mostly out of the bullpen, before finishing his major-league career in 2006.

While Guerra’s career is likely to be limited given the advanced age he begins his career, this year’s feat is already impressive given his age. Also, given that the future, by definition, has yet to happen, he has the greatest chance of having a lengthy successful career. While the White Sox should be credited for giving Guerra a chance, the Brewers are more than happy to reap the rewards as they took their own chance this season. Guerra has been a major bright spot in a rebuilding year for the Brewers, and it his performance, not his age, that is the main cause of that excitement.