CLEARWATER, Fla. - When they announced his name before the game Tuesday, the Phillies' rightfielder, the kid with so many questions to answer, trotted out of the dugout, slapped hands with his manager and four of his teammates, and fell in among them along the third-base line. He is 6-foot-5, with a fluid, athletic build and a swing that is both long and quick, and he has been productive if inconsistent over the sparse time he's been in the major leagues. He has the most powerful throwing arm of any outfielder in camp. The Phillies don't know yet exactly what they have in him. Their plan this season is to find out.

In this way, there is little new for the Phillies in having Aaron Altherr be their presumptive starting rightfielder. Those same qualities would have described Domonic Brown pretty well in 2012. And 2013. And 2014. And 2015. It became a rite of spring training here: the uncertainty over whether the Phillies would leave him in the lineup and allow him to develop, whether he had shed his sense of entitlement in which he coated himself after making the National League all-star team in 2013, whether the Phillies could afford to wait on his maturation any longer.

They finally tired of the perpetual drama and the unrealized promise, removing him in October from their 40-man roster. Brown signed a free-agent contract with the Toronto Blue Jays on Feb. 25, though he did not make the trip to Bright House Field on Tuesday for the Phillies' 5-3 loss in the teams' Grapefruit League opener. Altherr went 0 for 2 - grounding out to third, taking a called third strike, drawing a walk - and threw out a runner at the plate. He batted fifth in the lineup after batting third on Sunday against the University of Tampa. The Phillies are giving him a chance, and they want to see what he does with it.

"I know nothing's guaranteed," he said.

Over his 166 plate appearances with the Phillies - five of which came at the end of the 2014 season - Altherr has hit just .232 with 43 strikeouts, meaning he has struck out more than 25 percent of the time he has stepped into the batter's box. Brooks Baseball's PITCHf/x tool, an algorithm that tracks how hitters fare against certain types of pitches, revealed that Altherr was particularly susceptible to off-speed stuff. He was "exceptionally aggressive" against such pitches but had a "disastrously high likelihood" to miss them when he swung at them, posting a "whiff rate" of 55 percent.

When Altherr did make contact, though, he did damage. Against both fastballs and breaking pitches, according to PITCHf/x, his exit velocity - that is, the speed at which the baseball left his bat - was well above average, exceeding 92 mph. Twenty of his 33 hits went for extra bases, including five home runs, and his on-base-plus-slugging percentage last season was .827, the third-highest on the club. He had a double, a home run, and three RBIs in his first start, Aug. 19 against the Blue Jays, and he delivered arguably the most memorable moment of the Phillies' season: an inside-the-park grand slam against the Nationals on Sept. 25.

"After that," Altherr said, "it was like, 'Yeah, I can do this.' "

A ninth-round pick by the Phillies in 2009, Altherr had shown a tendency to walk too little and strike out too much over his seven seasons in the minors. That trend changed last year: At single-A Clearwater and double-A Reading in 2014, he walked 26 times and struck out 110 times in 492 plate appearances. At Reading and triple-A Lehigh Valley in 2015, he walked 49 times and struck out just 84 times over 489 plate appearances.

"It's more just being confident in my approach and my swing, not letting things get to me, just staying with it," he said. "But most of all, it's being able to trust myself and trust my approach, not getting outside what I'm looking for. If I'm looking for a pitch, don't swing at a ball that's not there."

The power people in the Phillies' player-personnel and player-development departments have noticed that improvement. They like Altherr's outfield defense, his strength, the maturity he has displayed despite being just 25. They acknowledge, too, that there's no telling how he might develop, or if he will. But the choice between signing a veteran rightfielder - Austin Jackson, say, or Jeff Francoeur - who would provide a more predictable level of production and determining exactly what they have in Altherr is, really, no choice at all. He will play. They will watch him. And everyone around here will hope that, come next spring, right field isn't a place for uncertainty anymore.