Since taking over full-time after Colby Rasmus was traded in 2011, Jon Jay has been the primary centerfielder for the Cardinals. He has produced solid results over those three seasons at a minimum salary. From 2011-2013, he put up a line of .291/.356/.396, good for a wOBA of .332 and 112 wRC+. He averaged seven homers and 12 steals, adding 4.8 runs above average on the basepaths over that time. His defense has been up and down, but according to UZR, he has come out less than one run below average during that time. He has accumulated 8.1 fWAR, good for a solid seventh among qualified National League centerfielders.
Unfortunately for Jay, a few factors led to a trade for Peter Bourjos and a potential drop in playing time in 2014. First, Jay is arbitration eligible and just settled with the Cardinals for $3.25 million in 2014, a figure likely to rise in 2015 should the Cardinals keep him. The second factor, and main culprit for the Cardinals exploring help at his position, is Jay's 2013 season. In a career high 628 plate appearances, Jay hit .276/.351/.370. Those numbers alone are not cause for alarm, especially at a premium defensive position. The problem for Jay last season was his defense.
Jay garnered national attention in the playoffs last season for misreading and failing to reach balls hit to the outfield. Taken alone, the errors in judgment could be just a blip, but advanced defensive metrics backed up the eyes of the nation. According to UZR, Jay was more than seven runs below average in center. Baseball Info Solutions' Defensive Runs Saved also had Jay as a negative in the field at -10.
UZR, available at fangraphs, goes back to 2002. Jon Jay has been an everyday centerfielder for the past three seasons, so I began in 2002 and looked at every qualified centerfielder with three straight years of playing time. For every year, beginning in 2004, I took a look at the player's UZR for that year as well as his current three-year average. Then I compared those numbers to how the player performed the next year if he qualified. There is some potential for survivorship bias as all remaining players were good enough to hold there position for four years. There were 48 such players. Next, I separated the players into buckets that matched Jay (with some overlapping): players whose value in the current year was lower than their three-year average, and players with a negative UZR in the current year. Jay's three-year average for 2011-2013 is -0.7. The results, along with the overall averages are below.
Not shown on the graph, the average change between the three-year average and the current year is 8.9 while the difference between the three-year average and the next year is 7.2. As you can see (hopefully anyway, as you may have to be signed into your google account to view the graph, sorry), players who have been in Jay's situation in the past have generally rebounded and returned to their three-year average after a poor year. Out of the 29 players who showed a lower current year compared to their three-year averages, 20 showed improvement the following season.
Jon Jay may end up like some of the other casualties who failed to make it to the next year due to the trade for Peter Bourjos, a superior defensive player no matter how well Jay rebounds. If given the chance, Jay does have a solid track record to fall back on, and many players in his position previously showed improvements just one year after an apparent decline.