For seven seasons, George Welsh, Navy's innovative head football coach, has convinced his players that the only way to win games was to play sound defense.

The Mids listened and obeyed; they finished among the top 25 teams in the nation in team defense three times in the last six years.

When Welsh delivers his customary sermon in Annapolis this year, the big question will be: Will the Mids listen again?

Graduation and position changes have left the defense units with a few big holes to fill. At the defensive end spot, Welsh will be using all inexperienced players.

The Mids will need help in the secondary. The most experienced player in the backfield, Fred Reitzel, has been switched to quarterback, and a handful of part-time players and key reserves from last year's team will vie for the cornerback and safety positions.

"We're strong up the middle on defense," said Welsh, who has put together back-to-back 9-3 and 7-4 won-lost records. "We have good linebackers and a strong trio of inside linemen. If we find some defensive ends and a good cornerback or two, our defense should be pretty good."

Defense will not be Welsh's only concern. Injuries nearly depleted his receiver corps last year and the loss of Bob Powers has left a big void at quarterback.

"We even have plans to throw more this year," Welsh said. "But, right now, I have no idea who the quarterback will be. Quarterbacks aren't that important anyway."

Welsh, a former Navy quarterback, hopes Reitzel, an excellent safety, can make the transition.

At the moment, Navy's strength lies in its running backs. Ed Meyers, who began the '79 season fourth string, vaulted into the top spot as a result of injuries and finished with a team high 651 yards on 106 carries and five touchdowns. The 5-9, 205-pound junior starred in his team's 31-7 victory over Army, churning out 278 yards on 42 carries, both school records.

Back to challenge Meyers for the No. 1 tailback slot is Mike Sherlock, who pulled a hamstring on a 59-yard touchdown run against William & Mary. Before that injury, the 5-11, 194-pound senior averaged 118 yards per game.

The offensive line will be anchored by 6-3, 260-pound All-America candidate Frank McCallister, whom Welsh calls one of the best linemen he has ever coached. McCallister is one of the main reasons Navy has totaled 4,500 yards running the last two years.

Curt Gainer, selected the best player during spring drills, is a capable tight end. Other experienced receivers are split ends Dave Dent and Troy Mitchell and wingback Greg Pappajohn.

"We have a lot of skilled positions but not a lot of experience," Welsh said. "In some places, we won't be as good as we've been and may have to settle for something less. But barring injuries, we should have a pretty good team."