The Buffaloes (9-2, 4-2) converted four field goals by Sergio Castillo then capped off the day with the lone touchdown of the game as Torrence Allen fell on a fumble in the end zone with 6:17 to play.
The Mustangs answered with a 1-yard run by Keidrick Jackson with 91 seconds to play and recovered the ensuing onside kick but were unable to move the ball down the field.
Midwestern State ends the season at 7-3 overall and 3-3 in Lone Star Conference play.
MSU senior running back Keidrick Jackson ran for a game-high 132 yards on 25 carries to close his sterling career as MSU's all time leading ball carrier at 4,003 yards.
Junior tight end Mark Strange added a career day with 117 yards on seven receptions as the Mustangs managed 284 total yards of offense.
The Mustangs were plagued by two interceptions -- both by John McSheffery -- with one coming on a jump pass thrown by Shavodrick Beaver in the second quarter after Jackson broke free on a 67-yard run to set MSU up at the 5-yard line.
MSU was unable to push the ball past the goal line on the first two down before Beaver's jump pass was read by McSheffery to thwart the drive. The second came on a 4th-and-10 attempt in the fourth quarter which set up the Buffs' lone touchdown drive.
The Midwestern defense led by Neiko Conway who finished with nine tackles, an interception and three pass breakups held the Buffs almost 200 yards off of the season average. West Texas A&M managed 315 yards on 74 offensive plays as Vaughan finished with 250 yards on 23-of-46 passing.
The NCAA will announce the Division II playoff field via web stream Sunday afternoon at 4 p.m. on NCAA.com.
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