BUFFALO, N.Y. (WIVB) — Josh Allen and Stefon Diggs made their preseason debuts Saturday night in Pittsburgh, but the star power didn’t help the Bills get off to a good start.

The Bills fell behind 14-0 and were out-gained 139 to 36 yards in the first quarter, when each team had three possessions. The Steelers made it 21-0 with a touchdown drive just before halftime.

“They out-coached us, they out-played us,” Bills coach Sean McDermott said following the 27-15 loss. “They wanted it more than we did. That was evident from the way that they played, and then on top of that, we’re beating ourselves with penalties.”

Allen completed 7 of 10 passes for 64 yards and scrambled into a six-yard loss in third down of his final drive. The Bills managed only three first downs on three possessions. Diggs (22 yards) and Gabe Davis (29 yards) each caught two passes from Allen, who completed an eight-yard pass to rookie tight end Dalton Kincaid on Buffalo’s first offensive play. James Cook rushed for three yards on three carries.

“I think on the offensive side of the ball, just lack of detail,” Allen said. “Pre-snap penalties, some post-snap penalties — those are going to happen — but you can’t have the pre-snap ones. So a lot to learn from. We’ll get in there, we’ll figure it out. It felt good to be back out there playing against another team. That’s a good team right there. They were hungry. They wanted it today, but a lot to learn from. I’m glad we’re going through this now as opposed to during the season.”

Buffalo’s offense was slowed by flags. Right tackle Spencer Brown was called for holding and an illegal block within three snaps on the second drive. Overall, the Bills were penalized 12 times for 90 yards in the first half.

“Absolutely unacceptable,” McDermott said.

The defense and special teams weren’t much better. Steelers running back Jaylen Warren scored on a 61-yard run on the opening series, and Kenny Pickett threw a 25-yard touchdown to tight end Pete Freiermuth right after Calvin Austin III returned a punt 54 yards into scoring range.

Matt Barkley was the second quarterback in the game for the Bills after Allen played the first quarter. Barkley led the Bills on a 70-yard drive before throwing an interception in the end zone. Kincaid and Trent Sherfield had 21-yard receptions on that series. Barkley, who had a strong performance in the preseason opener, threw a second interception before halftime and finished 7 of 12 passing for 93 yards, with a third interception and fumble coming in the third quarter. Kyle Allen was 12 of 15 passing for 112 yards and a touchdown toss to rookie Justin Shorter, playing with the third-string.

Mitch Trubisky, the former Bills backup, was 10 of 13 passing for 78 yards and a touchdown. Pickett completed 3 of 4 passes for 43 yards and a touchdown.

Buffalo’s top draft picks, Kincaid and offensive guard O’Cyrus Torrence were both in the starting lineup. Tight end Dawson Knox did not play due to a finger injury sustained in practice.

The Bills started Tyrel Dodson at middle linebacker and Dane Jackson at cornerback. A.J. Klein and Christian Benford played with the starters on the third series. Dodson and Klein both played with the second-team defense in the second quarter, providing little clarity on the Bills’ most prominent position battle. Tyrel Bernard miss his second preseason game with a hamstring injury.

Damar Hamlin, playing in his home city, made a tackle in the backfield on his first snap during the second quarter.