CLEARWATER, Fla. -- If the Phillies don't acquire a veteran starting pitcher in the coming weeks, what is Plan B?
Simple: They will have their most critical roster battle of the spring.
MLB.com is looking Tuesday at the biggest roster battles for every team in baseball. Everybody knows that Aaron Nola is a lock to make the Phillies' rotation. Jerad Eickhoff, Vince Velasquez and Nick Pivetta are favorites for three other jobs.
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Eickhoff is a favorite because of his solid performance before he battled injuries last season. He posted a 3.65 ERA in 33 starts in 2016, and many thought he could have been the Phillies' Opening Day starter in 2017. He possesses a dominant breaking ball, which he throws with regularity. If his command and velocity return to normal -- it was 91.6 mph in April before falling to 89.3 in August -- he should be a solid piece to the puzzle.
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Velasquez and Pivetta are favorites because the Phillies love their stuff, and believe they have considerable upside, although Velasquez could be running out of time to prove himself.
If those four stay healthy and pitch relatively well this spring, it likely leaves Ben Lively, Zach Eflin, Jake Thompson, Mark Leiter and Tom Eshelman competing for the No. 5 job.
Lively, 25, might be a slight favorite over the rest of that group because he posted a 4.26 ERA in 15 starts as a rookie. He competes, but front offices throughout baseball love swing-and-miss guys. Lively averaged only 5.28 strikeouts per nine innings. Only three out of 109 qualified starters last season had a lower rate: Jeremy Hellickson (5.27), Andrew Cashner (4.64) and Ty Blach (4.21).

Eflin, 23, posted a 6.16 ERA in 11 starts before finishing on the disabled list because of a strained right shoulder. He had surgery on both knees in 2016. Can he stay healthy? And if he stays healthy, can he pitch like the guy who had a dominant seven-start stretch in 2016, throwing two complete games and posting a 2.08 ERA?

Thompson, 24, was the top pitcher the Phillies acquired in the Cole Hamels trade in July 2015, but he has not yet fulfilled that hype. However, Thompson quietly posted a 3.27 ERA in eight starts last season, after struggling in Triple-A. But Thompson also averaged 4.27 walks per nine innings. Only three qualified starters averaged more walks per nine innings: Tyler Chatwood (4.69), Derek Holland (4.92) and Wade Miley (5.32). That number will need to improve to experience long-term success.

Leiter, 27, might be better suited in the bullpen, where he can give manager Gabe Kapler multiple innings. Leiter had a 5.19 ERA in 11 starts, but a 4.50 ERA in 16 relief appearances.
Eshelman, 23, has tremendous command. He has walked just 1.6 batters per nine innings in his Minor League career, including 1.0 in 18 starts last season at Triple-A. He is not on the 40-man roster, so unless he dominates, it is easier to see him opening again with the IronPigs. A strong performance this spring will put him in good position to be the first callup.