Jackie Bradley is still a risk for the Red Sox

Although Jackie Bradley Jr. is only 25 years old, he's endured more than a few highs and lows already in his career with the Red Sox. A heavily hyped prospect just three years ago, Bradley's star faded following a 2014 campaign in which he struggled mightily with the bat.

Last season, Bradley's story was one of redemption. Written off as little more than a future utility player, and someone the Red Sox were likely to trade away, Bradley instead crushed Triple-A pitching for over two months before showing off some impressive power in a 74-game stint in the big leagues. To most observers, Bradley looked as if he was finally coming good on that potential he had shown as a prospect.

All the fuss over Bradley these past few years essentially boils down to one undeniable fact: The dude can go get it in the outfield.

Defense has never been the question with Bradley, of course. How much he can hit, however, even after better results in 2015, remains a big uncertainty.

There's no denying that Bradley made some strides at the plate last season. After looking lost offensively back in 2014, the outfielder showed off surprising power this past summer, posting a .498 slugging percentage and .249 ISO that were vast improvements upon his previous major league numbers. He also raised his walk rate above 10%, a feat he'd yet to achieve against big league pitching.

Yet despite all this, there are still red flags that indicate Bradley is no safe bet to replicate this performance over the long-term. That Bradley enjoyed most of his 2015 success over a month-long period in August and early September should remind many of the perils of small-sample size results. That he did so while enjoying the good fortune of a .552 BABIP during that time should also be noted.

Even more worrisome is the fact Bradley never really solved the contact issues that plagued him during that ugly rookie campaign. After finishing with one of the highest strikeout rates in baseball in 2014, Bradley again struck out with alarming frequency last season. His 27.1% strikeout percentage would have ranked within the highest 15 among qualified hitters, and his swinging-strike rate actually increased from the year prior.

In fact, Bradley placed near the bottom of the league in just about every way one can measure a hitter's contact ability, performing far below the MLB average.

From inside the zone and outside to his overall contact percentage, which actually dipped even further despite his improved results, 2015 wasn't any better for Bradley in some respects.

When Bradley did put the ball in play last season, he feasted  on one pitch type with regularity: offerings left out and over the plate. The zone chart of Bradley's slugging percentage below demonstrates this reality:

Where Bradley proved especially susceptible, and where pitchers truly took advantage of his swing-and-miss tendencies, was on pitches outside the strike zone. This zone chart, which shows Bradley's percentage of whiffs for every swing,  paints a clear picture of where opposing hurlers took advantage of his contact problems:

Unless Bradley can duplicate the power output he posted in 2015, and that make other high-strikeout hitters like Chris Davis and Chris Carter playable, his production on offense will remain inconsistent at best. Consider that, after his hot six weeks at the plate, Bradley closed out the final month of the season with a .196/.286/.380 line over 106 plate appearances, including 29 strikeouts and 10 walks. Those numbers are far more in line with his ugly 2014 and could portend further struggles ahead, especially if opposing pitchers stop feeding him offerings up and over the plate.

The real key for Bradley in 2016 will be cutting down on all those strikeouts. He'll never be confused with Dustin Pedroia for his bat-to-ball ability, but he likely can't excel in the majors with a strikeout rate resembling that of Ryan Howard or Mark Reynolds either.

The good news, as has always been the case with Boston's young outfielder, is how much value Bradley brings to the table defensively. His play down the stretch in 2015 confirmed the many ways in which Bradley can impact the game outside the batter's box, and he remains an alluring talent because of that. And despite all the strikeouts, Bradley's increased power does leave room for some optimism that a corner has been turned

But for the Red Sox, who have an additional outfield question mark in Rusney Castillo, Bradley needs to produce next season. After all, they have few alternatives to turn to if Bradley again scuffles at the plate.

To sustain the success he showed in spurts last season, Bradley will have to do something he hasn't quite yet been able to achieve in the majors: cut down on his strikeouts. Even just a slight improvement in his contact results would go a long way toward making Bradley the everyday player the Red Sox have long hoped he'd become.