A clearer picture of the Phillies roster for Thursday's season opener came into focus on Monday night when it was announced that Tommy Hunter would start the season on the disabled list.

The righthanded reliever's mild hamstring strain, which manager Gabe Kapler said does not carry long-term concerns, opened a roster spot for both Jake Thompson and Victor Arano. The righthanders were competing for the final spot in the bullpen.

Hunter will join Mark Leiter Jr. and Jerad Eickhoff on the disabled list. Jake Arrieta will not be on the opening day roster but instead will either be activated from the disabled list or optioned from the minor leagues before he makes his Phillies debut on April 8.

Here's a look at the Phillies roster on opening day…

Catchers (2)

Jorge Alfaro: Alfaro has serious power potential and could grow into a real lineup threat. But the Phillies want him to focus on his catching. He worked this spring on his receiving and game-calling. Alfaro has an electric arm and is finding ways to better utilize it. The season will determine how much progress he has made.

Andrew Knapp: Knapp will likely receive the lesser share of playing time and is a more than capable backup. He worked on his defense this spring, altering how he plants his feet when throwing to second. Knapp, who reaches base at a high rate, has a good rapport with the team's young pitchers.

Infielders (6)

Carlos Santana: The first baseman's arrival seemed to shift the expectations for the season because he was the first free-agent splash of the Matt Klentak era. Santana walks almost as much as he strikes out and is a strong presence in the clubhouse. Manager Gabe Kapler loves his approach and plans to bat him second or fourth.

Cesar Hernandez: The Phillies say Hernandez is their starting second baseman, but there is no doubt he is looking over his shoulder now that Scott Kingery signed a long-term deal. Hernandez is no pushover and he is coming off a career-best season. But his time in Philly could be coming to a close.

J.P. Crawford: There seems to be almost no pressure on the team's former No. 1 prospect:  He will likely begin his first full season batting ninth, behind the pitcher. Kapler wants Crawford and his high on-base skills to be effectively a second leadoff hitter and turn the lineup over. Crawford said he's fine with that.

Maikel Franco: His new batting stance has looked good this spring, as the third baseman is now able to connect with outside pitches. But the true test will be how he fares in the regular season, a campaign that will likely determine his future with the team.

Scott Kingery: It was almost guaranteed that Kingery would start the season at triple A before he signed a six-year contract just days before opening day. Kingery is a natural second baseman but will be used all over in order to get him playing time. The Phillies have loved his attitude: Kapler called it the model of teammate behavior.

Pedro Florimon: Florimon is a professional utility man and was used in that role last season before he broke his ankle in September. The Phillies need Florimon to be nothing more than a dependable bench player.

Outfielders (4)

Rhys Hoskins: He had a great camp and looks ready to build off the 18 homers he hit in 50 games. He's made some adjustments to be able to hit inside fastballs better, something he thought pitchers were beginning to target him with. Hoskins devoted a lot of time in spring training to working on his defense in left field and he seems to be more comfortable.

Odubel Herrera: He turned it on last season after a slow start, batting .324 with a .377 on-base percentage in his final 50 games. That is the production Herrera will need to stay in the lineup. The Phillies suddenly have a glut of outfielders they need to find playing time for.

Nick Williams: Williams looked good last season and worked this spring on his approach at the plate. That was evident when he jumped Boston's Chris Sale for two first-pitch hits earlier this month. Williams said he went into each at-bat expecting a first-pitch fastball. That's what he got.

Aaron Altherr: He might be the best defensive outfielder the Phillies have. Altherr can play all three positions but will spend most of his time in a right-field platoon with Williams. A healthy Altherr would be a key piece of the lineup.

Starters (4)

Aaron Nola: Nola looked strong this spring as he gears up for what the team hopes can be a season that defines him as one of baseball's elite young arms. The righthander has an elite curveball and is constantly trying to develop his change-up. He will be the youngest Phillies pitcher to start on opening day since 1964.

Nick Pivetta: The Phillies asked Pivetta to throw his fastball higher in the zone and he looked more comfortable elevating the pitch later in camp. The front office believes strongly in Pivetta and he'll have a chance this season to prove the brass right. He'll start the second game of the season.

Vince Velasquez: He has the talent to be a special pitcher but has failed to put that talent to consistent use. He has to learn to be economical with his pitches and last past the fifth inning or else the calls for him to go to the bullpen will become louder. Velasquez will start the third game of the season.

Ben Lively: Lively competed all spring for the final spot in the rotation and was able to win it in the final week of camp. He does not blow hitters away but is able to find success with good command of his two-seam fastball.

Relievers (9)

Hector Neris: He'll be the closer or at least he'll be the pitcher who is used more often than others in the ninth inning. Kapler avoids labels and roles. Neris emerged last season as a solid closer and it makes sense to keep him where he's comfortable.

Pat Neshek: He turned down a better offer from Colorado to return to the Phillies. He was happy to see pitching coach Rick Kranitz stay on board after the rest of last year's staff was dismissed. Kapler, shying away from roles, could opt to use Neshek depending on the match-up and not just the inning. He said he'll be ready to pitch once the sixth inning starts.

Luis Garcia: He looked to be on his way out of the game after starting last season in the minors. Garcia instead rebounded and had a great second half. Garcia tapped into his power arm last year, found his control, and seemed to master the splitter that Neris taught him.

Edubray Ramos: He had to go to triple A last year to regain his confidence, but he came back with a new mind-set and a dominant slider. Ramos carried that confidence into spring training and racked up the strikeouts while giving the Phillies the mound presence they sought.

Hoby Milner: Milner found success last season without having a breaking pitch. The lefthander started throwing a spike curveball this winter and believes it is the pitch he needs to get both lefthanders and righthanders out. He was dominant against lefthanders last year but had little success against righthanders.

Adam Morgan: Morgan was a great story last season as he transitioned from failed starter to dominant reliever. His fastball played well out of the bullpen, seeing a spike in velocity. He'll have the chance to continue that story this year while playing a key role.

Drew Hutchison: He joined the Phillies midway through camp on a minor-league deal and pitched well enough to earn a role as a long reliever. He could be used to piggyback another starter who can last only a few innings.

Jake Thompson: Thompson moved to the bullpen this spring and it is a switch that could save his career. The Phillies think he has a slider that's fit for a major-league relief role. He was once a top pitching prospect and has showed some flashes in the minors but no longer had a rotation spot. A bullpen move made sense.

Victor Arano: He looked as if  he belonged in the majors last September in a 10-game stint. The 23-year-old has kept his walks to a minimum this spring and has a power fastball to be solid piece in the bullpen. Hunter's injury opened up a big opportunity for him to see some meaningful innings.