This year Jon Jay had everything working for him except the depth chart. He played behind Ryan Ludwick and Colby Rasmus, two vaguely fragile outfielders, and he got off to a hot start in Memphis after an outwardly adequate but disappointing AAA debut in 2009. At 25 and relatively tool-free he was old enough and polished enough that the Cardinals wouldn't be afraid to put him on the bus.
The only problem was the depth chart. Jay came into the season behind Tony La Russa's Professional Hitter, Nick Stavinoha—even older, even less toolsy; Allen Craig, Nick Stavinoha's Viva El Birdos-approved equivalent; and Joe Mather, a center fielder who had the added bonus of being platoonable with Colby Rasmus. In the Cardinals' crowded outfield—more specifically, on its young, crowded bench—there seemed little room for Jay.
But Craig vanished after hitting line drive after line drive for outs, Mather vanished after not hitting any line drives, and Nick Stavinoha's truly uncharacteristic outfield daredevilry landed him on the Disabled List, and now even with Randy Winn on the roster Jay finds himself another hot month away from earning the Team Store a shipment of t-shirt jerseys with his name on them. In July he's hit .467, with two home runs and four doubles; he's scored six runs and driven in six more himself.
The Jon Jay story starts in 2006. He was the Cardinals' second round pick, coming after Adam Ottavino in the first and Brad Furnish and Chris Perez in the supplemental rounds, and he was an odd choice. He was a tweener with a big hitch in his swing—a college performance guy who didn't project to have enough power to stay in a corner and didn't quite get plaudits for his work in center. He seemed to be drafted in part to become a fourth outfielder, though a the time I thought his swing vaguely resembled Ray Lankford's and was happy enough with that to forgive the Cardinals' their low-upside trawling. (It didn't hurt that his inadvertent namesake, Founding Father and original Chief Justice John Jay, provided—and has provided ever since—a wealth of nickname opportunities.)
Jay signed extremely quickly and was immediately sent to full-season ball at Quad Cities, where he hit .342/.416/.462 over 60 games. Already in the process of experiencing Nick Stavinoha's fall from grace after doing polished-college-guy damage in the Quad Cities the year before—he'd hit .344/.398/.564 upon signing in 2005, only to hit .297/.340/.460 in his AA engagement in 2006—we might have underrated him a little then.
But the main thing that made Jay into an interesting complementary piece happened outside of his Baseball-Reference page. While he waded up the ladder in 2007, 2008, and 2009 the scouting report changed; like Colby Rasmus before him he'd gone from an adequate center fielder to an outstanding defensive outfielder. Suddenly his lack of power projection seemed less urgent. 2007 was marred by injuries and an aggressive promotion to AA that didn't take; 2008 saw his bat perk up in AA, but 2009 saw him disappoint in Memphis. As his bat struggled to acclimate to higher altitudes his defensive reputation grew better and better.
So in 2010 he had his chance, after the improbably disappearance of his various rivals, and thus far he's taken it better than anyone could possibly have expected. The best case scenario for Jay, I think, is Randy Winn, the player who briefly took his job. At his best—as an All-Star by default with Tampa Bay, as the player useful-but-replaceable enough to be traded for Lou Piniella—Randy Winn combined a high average and doubles power with outstanding defense in right field. He was as valuable as second-tier sluggers like Andre Ethier without looking it, the kind of stealth value that's rewarded with extremely team-friendly arbitration numbers.
Of course, Winn hit 20 home runs at his best, and while the gap between them wasn't as wide when Winn was a minor leaguer it's always tricky to project a player to triple his current career high in home runs. If Winn is the 75th percentile projection, the one that turns Jay into the surprise replacement for Ryan Ludwick, a more reasonable (but still useful!) outcome might be to visualize Jon Jay as a kind of turbocharged version of Skip Schumaker The Outfielder.
Jay's minor league numbers are better—.301/.367/.432, to Schumaker's .290/.354/.385—and he's reached the Major Leagues in an extended tryout two years earlier. Most importantly for a player who probably won't follow Schumaker to second base, he's a truly excellent outfielder; Schumaker has a fine arm, but his defensive reputation seemed to flow, as a backup catcher's, from his inability to hit for power.
It's not in my nature to make a lot of predictions, but it's fair to bet that Jon Jay won't continue to push his average over .380. But if his 2010 numbers are any indication, there's nothing in his five years with the Cardinals organization to suggest he couldn't become one of the most valuable fourth outfielders in baseball.