Breaking out at the Major League level is hard. Repeating that success may be even more difficult.
Opponents adjust, injuries strike and natural regression takes its toll. So for every Michael Trout who puts up huge numbers year after year, there are plenty of players who soar one season and fizzle the next.
With Spring Training now underway -- and the 2017 campaign quickly approaching -- it's a good time to consider five position players whose numbers jumped significantly last season. Why might each maintain that progress and, conversely, why might that prove to be a tall task?
Keep in mind, while all five of these hitters saw their power numbers spike in '16, the same was true of the Majors as a whole, which saw an increase of 701 home runs and 12 points of slugging percentage.
Daniel Murphy, 2B, Nationals
2016: 582 PA, .347/.390/.595 (156 wRC+), 25 HR, 104 RBI, 4.6 WAR
Repeat the feat: Murphy was already a stellar contact hitter before he blitzed the 2015 postseason for seven home runs over his first five games. He carried that pop into '16, when he finished second in the National League in wRC+, as well as in the league's MVP Award voting. While surprising, his step forward wasn't a fluke, given that Murphy made real changes to his approach and swing. According to Statcast™, his average launch angle jumped from 11 degrees to 17 degrees, putting him in line with the likes of Anthony Rizzo, while helping him finish in MLB's Top 20 in isolated power, just ahead of Jose Cabrera.
Pump the brakes: Just because a breakout was legit, that doesn't mean it will be duplicated. Just ask Murphy's teammate, Bryce Harper, who followed up a sensational 2015 with a pedestrian '16. Murphy will turn 32 on April 1, and was slowed late last season by a strained left glute. It's also worth noting that each of the previous 17 times that a player batted .340 or better since 2006, his average dropped the next season -- by an average of nearly 40 points.

James Dozier, 2B, Twins
2016: 615 PA, .268/.340/.546 (132 wRC+), 42 HR, 99 RBI, 6.5 WAR
Repeat the feat: Dozier, who homered a total of 16 times in more than 1,600 Minor League plate appearances, bumped his career high all the way from 28 to 42 last season. How? He mastered the art of hitting the ball in the air to left field, as he led the Majors in pull percentage for the second straight campaign. That sounds simple, but while Dozier doesn't have huge raw power, his ability to drive and elevate the ball in a favorable direction is a huge help.
Pump the brakes: Yes, Dozier is coming off a red-hot second half. But it's also true that not so long ago, he was buried in a horrific slump. The 29-year-old hit just .205/.282/.354 with 17 homers over 565 plate appearances from the beginning of July 2015 to the end of last May. In '15, when Dozier posted a roughly league-average 102 wRC+, his walk rate, strikeout rate and batted-ball profile looked much the same as in '16.

Christian Yelich, CF, Marlins
2016: 659 PA, .298/.376/.483 (130 wRC+), 21 HR, 98 RBI, 5.3 WAR
Repeat the feat: After posting a 118 wRC+ in each of his first three seasons, Yelich boosted his production by bumping his career high in homers from nine to 21, and his isolated power from .119 to .185. Such growth wasn't surprising for a physically maturing former top prospect in his age-24 season. Always an extreme ground-ball hitter, Yelich got the ball in the air a bit more in 2016 and posted a BABIP above .350 for the fourth straight campaign.
Pump the brakes: Yelich still posted MLB's fourth-highest ground-ball rate -- and second-lowest fly-ball rate -- last year, while his homers-per-fly-ball rate was eighth-highest. In other words, his power surge may be tough to maintain, unless he continues to lift the ball more frequently. Defensively, he will have to handle the transition to being a full-time center fielder.

Jean Segura, SS, Mariners
2016: 694 PA, .319/.368/.499 (126 wRC+), 20 HR, 64 RBI, 5.7 WAR
Repeat the feat: Following a solid first full season with the Brewers in 2013, Segura endured two tough years, during which he dealt with personal tragedy and freak injury. A trade to Arizona provided a clean slate in 2016, and Segura took advantage at an age (26) when many players are hitting their stride. In doing so, he made significantly better contact -- with his average exit velocity rising from 87.3 mph to 89.9 mph and his average launch angle from 6 to 12 degrees.
Pump the brakes: Segura faces a couple of obvious challenges in 2017, aside from elevated expectations. For one thing, Seattle will slide him back to shortstop from second base, where he started 142 games in '16. For another, moving from the desert to Safeco Field will put him in a more challenging hitting environment, although Segura also did quite well on the road last season (.312/.375/.468). Even given his speed, he could find it tough to replicate a .353 BABIP that exceeded his previous career total by 52 points.

DJ LeMahieu, 2B, Rockies
2016: 635 PA, .348/.416/.495 (128 wRC+), 11 HR, 66 RBI, 5.2 WAR
Repeat the feat: The 28-year-old has flown under the radar in Colorado, despite a 2015 All-Star selection and a '16 batting title. Yes, LeMahieu enjoys Coors Field (1.064 OPS last year), but he also ripped the ball with authority -- as his 92.5-mph average exit velocity ranked 12th in MLB (minimum 300 batted balls), roughly even with Yoenis Cespedes and Paul Goldschmidt. LeMahieu improved across the board, raising his walk rate, cutting his strikeout rate and making more contact, all while increasing his power output.
Pump the brakes: LeMahieu's ability to put the bat on the ball and use the opposite field should give him a fairly high floor. But even given his history as a high-BABIP hitter, last year's .388 mark (including .420 at home) will be tough to repeat. That figure represented a 26-point leap, and was the highest in the Majors by a qualified batter since 2013.

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