Can Carlos Beltran keep up his strong performance so far?

Down the stretch in 2015, Carlos Beltran was one the Yankees' best hitters. He posted a .292/.364/.513 slash line in the second half, helping prop up a flagging offense. Beltran has continued the act in 2016. His .263/.290/.537 line equates to a 119 wRC+, the best on the team. With the Yankees ranked 25th in league and park adjusted offense, Beltran's performance has been one of the only things keeping the lineup afloat.

The most striking thing about Beltran's play is that he is even capable of achieving such heights this deep into his career. His 120 OPS+ ranks 21st since 1961 among all age-39 seasons, according to the Baseball Reference Play Index. His .537 slugging percentage ranks 8th among that group. It is somewhat shocking that Beltran, who looked all but washed up two years ago in his first year as a Yankee, has seemingly improved with age during his time in New York.

Nearly as striking has been the extreme way in which Beltran has performed. The shape of his production sticks out when compared to the rest of his track record. Nearing age 40, Beltran has posted his highest isolated slugging figure since 2006, his second season with the crosstown Mets. Same goes for his slugging percentage. With 12 home runs in the team's first 48 games, Beltran is on a 41 home run pace. That would tie his career high, which was also set during that 2006 season.

Yet even with Beltran's remarkable late career power surge, the overall value of his production isn't out of line. That is due to a nearly as surprising drop in walks. His walk rate of 4.3% is far below his career average of 10.1%, and would be a career low. Just last season, Beltran walked in 8.5% of his plate appearances. Beltran has always been considered to be a relatively patient, disciplined hitter. It is jarring to see him ranked 157th out of 181 qualified hitters in walk rate.

How has Beltran been able to bring impressive power, even as his declining walk rate hints a declining skill set? For starters, over 20% of his fly balls have flown over the wall. Such a home run rate smacks of possible good fortune. According to Statcast, Beltran's average home run has flown 383 feet. That ranks an unimpressive 258th among hitters with at least 30 batted balls on record. It seems likely that Beltran's HR/FB% will regress if balls like this start to hit the wall, rather than narrowly clearing it:

Elsewhere, nothing sticks out of his batted ball profile to indicate Beltran has been particularly lucky. He still has a healthy fly ball rate (42.8%) and hard contact rate (33.3%). However, to go along with Beltran's declining walk rate and possible good luck when it comes to home runs and fly balls, there are some other concerning signs that suggest Beltran might have a tough time keeping this up.

As his walk rate has deteriorated, so have his overall plate discipline markers. The rate of pitches Beltran has seen in the zone has increased since last year (from 43.2% to 47.2%), but the rate at which he has swung at those pitches has fallen (66.9 % to 65.7%), indicating he has been letting strikes go by. More concerning are his contact rates. Beltran has made contact with pitches both in and out of the zone at a lower rate than last year, and his overall contact rate of 81.1% would be his lowest in five years.

Turning to Brooks Baseball, it becomes apparent where Beltran has struggled. Here are Beltran's whiffs per swing rates during his time in New York, against hard, breaking, and offspeed pitches:

Beltran hasn't had too much trouble with fastballs, but it is clear breaking and offspeed pitches are beginning to give him fits. He is swinging and missing on over 32% of swings at breaking balls and 31% of swings at offspeed offerings.

His overall results against such pitches further cement the trend. In 2016, Beltran has hit .270 with a .778 slugging in at-bats ending with a four-seamer, and .405 with a .622 slugging in at-bats ending with a two-seamer. Contrast that with his .100 batting average against sliders, his .115 batting average against curves, and his .220 mark versus changeups. Beltran has had trouble simply putting bat to ball on pitches that aren't fastballs, and even when he has put them in play, he has not done any damage.

Such troubles do not bode particularly well for Beltran's future performance. Still, he has spent the past year proving nay-sayers wrong, and he has been the best power performer on the Yankees by far this season. Even so, if he keeps this up, it would be rather unprecedented. In baseball history, no player of Beltran's age or older has ever maintained a sub-.300 on-base percentage and a slugging percentage greater than .500 for an entire season.

The Yankees must hope Beltran can continue hitting. Outside of perhaps another middle-aged Yankee, Alex Rodriguez, no other player looks likely to provide this kind of power. A quick look at Beltran's power numbers gives the appearance of a player hitting better than ever. A closer look at his performance depicts an aging player with declining skills, and now, Beltran may even have to contend with injury troubles. Only time will tell if Beltran can continue to defy age and help keep the Yankee offense alive.