Football coaches have a tendency to call in their reserves early in preseason games. Take the Buccaneers’ preseason opener Thursday against the Baltimore Ravens for example.

The Bucs were only a couple of plays into their second offensive series when coach Greg Schiano began pulling his starters. By the start of the second quarter Ravens coach John Harbaugh had pretty much pulled all of his.

So why then was starting left defensive end Da’Quan Bowers the Bucs’ projected replacement for 2012 sack leader Michael Bennett still playing as the clock wound down at the end of the first half?

“Because I felt that I needed to’’ Bowers said Saturday. “I’m an unproven defensive end in this league and I felt that I needed the extra work. So I talked to coach (Schiano) about it and he agreed.’’

Oh Schiano agreed all right. Though he has largely tempered his comments on the matter the second-year coach has made it clear in recent days that he has not been overly pleased with Bowers’ performance this training camp.

He has openly questioned the consistency of Bowers’ effort in practices and has expressed concern about the third-year pro’s ability to make the transition from situational pass rusher to every-down player.

His displeasure is such that you get the feeling it was Schiano who called the meeting with Bowers and Schiano who laid out the plan for Bowers to play the entire first half against Baltimore.

“I want to see (Bowers) play hard play after play after play’’ Schiano said prior to Thursday’s kickoff. “He needs to string together some plays where he’s going at a high level. (We’ve seen that) on and off (in practice) but it needs to be better.’’

By Schiano’s gauge Bowers’ did play better and harder against the Ravens on Thursday. But the 2011 second-round draft pick’s two-tackle effort still didn’t meet Schiano’s expectations for consistency.

“Some good some not so good’’ Schiano said when asked to assess Bowers’ play in the Bucs’ 44-16 loss. “What we need is a little more good and a little less not so good and to keep tipping the scale the way we want it.’’

Bowers and Schiano agree on that point as well. Bowers graded his play so far this preseason as just “OK’’ openly admitting he has “a lot of work to do before (the Bucs) go to New York’’ for their Sept 8 regular-season opener against the Jets.

What Bowers needs to work on most is his conditioning. After more than two weeks of workouts he still has a tendency to work through the final live 11-on-11 drills at what appears to be a walkthrough pace.

“I still get a little winded at times’’ Bowers said. “I’m not in the best shape. I’m still getting used to the speed of practice. But other than that it’s been decent.’’

The conditioning issues haven’t come as a total surprise. Though he worked diligently to prepare himself for every-down duty — losing more than 20 pounds during offseason workouts — Bowers is unaccustomed to the rigors of training camp.

He saw only limited action in camp as a rookie after undergoing offseason knee surgery and missed all of camp last year after suffering a torn Achilles tendong that also forced him to miss the first six games of the season.

Throw on top of that the fact that this is the first time since his last year in college that Bowers has played an every-down role from a fitness standpoint he clearly has some catching up to do.