STILLWATER, Okla. (AP) - Gary Patterson decided to make his own quarterback change after Oklahoma State did it earlier in the first half.
The switch didn't work out as well for the TCU coach on Saturday.
Tyler Matthews fumbled on his first place under center, and the Horned Frogs couldn't produce enough offense after they went back to starter Trevone Boykin in a 24-10 loss to No. 21 Oklahoma State.
Boykin completed only 17 of 35 passes for 188 yards with three interceptions, and TCU's four turnovers prevented them from spoiling Oklahoma State's homecoming.
''When you play at somebody else's place, you have to play to win,'' Patterson said. ''We hadn't been down there (in the red zone) very often, but when you get down there, you have to get more than three points.''
Clint Chelf made a case for why he should again be Oklahoma State's starting quarterback, completing 10 of 25 passes for 178 yards with one interception for the Cowboys (5-1, 2-1 Big 12 Conference).
The senior, playing in his final homecoming game, replaced starter J.W. Walsh after the sophomore threw his second interception of the first half, an ill-advised throw into the middle of the end zone.
Chelf responded after having his first pass intercepted and led the Cowboys on back-to-back scoring drives to help them build a 17-0 halftime lead.
TCU (3-4, 1-3) also switched quarterbacks in the second quarter, but it didn't help as the Horned Frogs struggled in their second trip to Stillwater in as many years.
''We felt like we needed a spark on offense and so we made a change and played Clint,'' Gundy said. ''So we'll evaluate our offense this week and our game plan for the next team and decide which direction we want to go.''
Josh Stewart added 10 catches for 141 yards and had a 95-yard punt return for a touchdown, giving Oklahoma State enough offense to overcome four turnovers and a pair of missed field goals.
''We doubled him, we played over the top of him and he still found ways to get there,'' Patterson said of Stewart.
Oklahoma State had hoped to get off to a fast start following its second bye week in a month, but other than Stewart, things didn't go well at first.
Stewart did everything he could in the first half, catching eight passes for 106 yards and giving the Cowboys a 7-0 lead with his 95-yard punt return toward the end of the first quarter. He fielded the punt at the 5-yard line, darted across midfield and made several nice cuts on his way to the longest punt return in Oklahoma State history.
Stewart finished with 265 all-purpose yards, with 124 yards coming on punts to go along with his 141 yards receiving. Afterward, Gundy said it would be hard to disagree with the statement that Stewart was the ''best player on the field'' Saturday.
''When you hear stuff all week about the level of secondary you will be playing against, it makes me want to make plays for my team,'' Stewart said. ''I had opportunities, and I just made the best of them.''
Walsh finished 9-for-18 for 115 yards and two interceptions, but his status as Oklahoma State's starting quarterback remains in jeopardy.
Chelf beat out Walsh to start Oklahoma State's season-opening win over Mississippi State, and he might get another chance to lead the Cowboys' high-powered offense.
''There were a couple of throws that didn't look good, but I think there was a reason for that,'' Gundy said of Chelf's performance. ''Overall, I thought he managed the game pretty well.''
Patterson decided to insert Matthews at quarterback after watching his offense struggle while falling behind by 17. Boykin completed only 5 of his first 13 passes for 27 yards with two interceptions, but Matthews couldn't provide any more consistency.
Matthews fumbled on his first play and failed to complete his only pass. Boykin returned to the lineup to start the second half, but he appeared to struggle with an injury and ended the third quarter by throwing his third interception.
The Horned Frogs got within 17-10 when Waymon James slipped past Oklahoma State defensive tackle Calvin Barnett and scored on a 14-yard touchdown with 7:39 remaining.
However, Rennie Childs' first career touchdown on a 7-yard run with 6:04 remaining ended TCU's hopes of sparking a second-half comeback.
''We came out in the second half with our backs against the wall, and that's when we play our best football,'' TCU offensive lineman Eric Tausch said. ''If we could only play like that in the first half, then the sky's the limit for our offense.''
The Horned Frogs briefly found an offensive rhythm when Boykin connected with Deante' Gray for a 69-yard reception with less than four minutes left in the third quarter. But TCU lost two yards on its next three plays and had to settle for a 35-yard field goal that cut Oklahoma State's lead to 17-3.