Baltimore Coach Frank Kush has never tried to fool anyone into believing the Colts are ready to challenge the National Football League's best, and his team showed why today.

The Colts became unglued in the seconf half and lost to the New England Patriots, 24-13, before 40,574 at Memorial Stadium. The Colts were tied at halftime, 10-10, but faltered in the second half when rookie Mike Pagel, the youngest quarterback to start an NFL game in 14 years, played little because of a mild concussion suffered late in the first half, but I knew it was only a matter of time before their strength took over."

The Colts, with only 19 players from last year's 2-14 team, probably couldn't have picked a better opening-game opponent than the Patriots, the only team they beat last year. But New England, under new Coach Ron Meyer, looked further along in its rebuilding than the Colts.

Today, the Colts were jittery in critical situations, but the Patriots were opjortunistic, converting a pass interception and a fumble recovery into second-half touchdowns. TIn the most dramatic changes from last season's 2-14 Patriots, Meyer replaced quarterback Steve Grogan with Matt Cavanaugh and used a conservative, run-oriented offense. Cavanaugh threw only 16 passes, completing seven for 103 yards and two scores. In contrast, three Colt quarterbacks threw 46 passes.

The Patriots' big-play man was running back Tony Collins, who rushed for 137 yards on 21 carries and caught four passes for 56 more and a touchdown.

The Colts' offense played well in the first half with Pagel at quarterback, but his injury forced Kush to use David Humm and Art Schlichter most of the second half. They were a combined 13 of 31 with an interception each.

Pagel was at his best when the Colts drove 80 yards in 14 plays for a touchdown late in the half. But he also suffered the concussion on that drive.

He completed four of four passes for 51 yards in the drive and scored the touchdown on a one-yard run. The touchdown was set up when Pagel, facing fourth and one at the five, picked up the first down with a rollout keeper.

But he sustained a concussion on that play, when New England linebacker Larry McGrew tackled him hard and out of bounds at the three. He stayed in the game long enough to score the touchdown that put the Colts ahead, 10-3, with 4:17 remaining in the half.

Pagel didn't play again in the half and only two series midway through the third period. In six plays, he was sacked, threw two incompletions, fumbled a center snap and threw his only interception. "I thought I was okay after I rested at halftime," said Pagel, "but after I went back in, my sense of balance was bad and things started getting hazy."

The Patriots tied the game at 10 before halftime on a 15-yard touchdown pass from Cavanaugh to Collins and Rex Robinson's conversion.

With Humm at quarterback, the Colts moved into position for Mike Wood's 30-yard field goal and led, 13-10, with 8:58 left in the third quarter. On the Colts' next possession, though, Humm was intercepted by Ray Clayborn, who returned the ball to the Colt 31. Two plays later, Cavanaugh threw a 30-yard touchdown pass to Ken Toler. Robinson's conversion put the Patriots up, 17-13.

Early in the fourth quarter, Cleveland Franklin dropped a handoff from Humm and the Patriots recovered at the Colts' 21. New England rookie Robert Weathers scored on a one-yard run six plays later.

The Colts were driving late in the period when Schlichter was intercepted by Don Blackmon.