The Navy football team began spring practice today not only minus their two senior captains but also without defensive coordinator Buddy Green, who is recovering from gall bladder surgery.

According to Navy officials, doctors have told the two-time nominee for national assistant coach of the year to take his time as he heals from the procedure, and there is no definitive timetable for when he will rejoin the team.

The Midshipmen already are without defensive end Jabaree Tuani and fullback Alexander Teich, both of whom are recovering from offseason surgery,and are scheduled to miss all of spring practice for precautionary reasons.

Those absences mean this spring practice is as much about seeking leadership from some less experienced players as it is implementing strategy. That task is all the more challenging on defense considering turnover was especially high on that unit. Among the most dependable players who are set to graduate are safety Wyatt Middleton, linebacker Tyler Simmons and defensive end Billy Yarborough.

Some of last year’s marquee players, including quarterback Ricky Dobbs and tackle Jeff Battapaglia, attended the opening of spring practice to provide encouragement and perhaps give pointer here and there to some of the less seasoned players. But everyone in the program is well aware a new group must emerge in order for the Midshipmen to continue their unprecedented success of much of the past decade.

Navy is coming off a season in which it went 9-4, including victories over Notre Dame and Army, to extend its school record of consecutive bowl appearances to eight. The Class of 2011 also tied the program’s modern-day record for career wins with 35.

“It’s an opportunity not only for other guys to get reps, but also for a chance to see who are some leaders,” Coach Ken Niumatalolo said. “Guys we haven’t seen in the past, they’ve got to step into some leadership roles. It’s kind of cool to have guys come back as student-coaches. It’s an opportunity for other guys to step up. That’s the great thing about this place. There’s always somebody ready.”

Among the more untested units is the secondary, and compounding that is the loss of Middleton, who was the team’s most dynamic playmaker and perhaps its most indispensable player overall. He started 52 of 54 games and last season had a 98-yard interception return for a touchdown against Army — the longest in series history — in a 31-17 victory at Lincoln Financial Field.

Also gone from the secondary are De’Von Richardon, a starting safety who was dismissed from the academy earlier this year for academic reasons, and graduating seniors Kevin Edwards and Emmett Merchant.

This year’s depth chart in the secondary comprises just one player with more than two starts last season, that being Kwesi Mitchell. The senior cornerback started 12 games at cornerback and one at free safety.

“We just got to have some guys emerge,” Mitchell said. “I’m trying to lead the DBs. I’m going to do my best especially because we’re missing Wyatt, Kevin and Merchant, so me being the only starter left, I’m going to do my best to lead those guys.”