Stillwater, Okla. ? Senior right-handed ace Frank Duncan hadn’t surrendered a home run all season.

Until Sunday.

Duncan allowed two long balls, and Oklahoma State completed the Big 12 baseball sweep of Kansas University, 6-3.

“He (Duncan) wasn’t as sharp today as he’s been the last four times out in conference play,” KU coach Ritch Price said. “He left some balls up, and when you’re red-hot as hitters, you take advantage of mistakes, and they were physical with the bat today. They hit those two homers, and that was the difference in the ballgame — they hit two, and we hit one.”

That one — Tucker Tharp’s two-run shot in the second — gave KU (23-19, 6-9) a 2-0 lead.

But Tim Arakawa’s three-run homer in the bottom of the frame gave 13th-ranked OSU (29-11, 11-4) a 3-2 edge.

Dustin Williams then homered off the glove of a leaping Tharp in center field in the fourth to make it 5-2

The sore spot on the weekend for the Jayhawks came from the middle of the lineup. Junior left fielder Michael Suiter had just one RBI, while Big 12 RBI and home run leader, junior right fielder Connor McKay, managed zero, hitting into two double plays.

“The middle of the lineup got pitched really tough this weekend,” Price said. “The only way we are going to win is if the 3-4-5-6 guys in our lineup produce. McKay goes the weekend without an RBI, and Dakota Smith doesn’t get an RBI, and Suiter only has one, and if that happens, we are going to get beat.”

Kansas will host Missouri State at 6 p.m. Wednesday before returning to Big 12 play Friday at Baylor.

Kansas 020 001 000 — 3 9 0

Oklahoma State 030 200 10x — 6 7 0

W — Blake Battenfield, 2-0. L — Frank Duncan, 4-2. Sv — Brendan McCurry, 11

2B — Aaron Hernandez, KU; Zach Fish, OSU. HR — Tucker Tharp, KU; Tim Arakawa, Dustin Williams, OSU.

Kansas highlights — Colby Wright 3-for-4, R; Tucker Tharp 2-for-4, R, 2 RBIs; Justin Protacio 2-for-3.