The Terps suffered their fifth loss in the national championship game under coach John Tillman.
DeMaio needed just 39 seconds of overtime to claim a victory for the Terps and set a date with Duke in the semifinals.
Jared Bernhardt led the way, scoring six goals for the Terps, earning a first round victory over the Catamounts.
Three late goals helped the Terps beat their rivals and clinch their third Big Ten championship.
Bernhardt's career-high eight goals and 10 points helped him become the Terps' all-time leading points scorer.
Wierman took over the starting job from senior Justin Shockey, winning nine of 13 faceoffs in the first half.
The Terps went on a 7-0 run in the second and third quarters, including a strike from goalie Logan McNaney.
Despite not seeing many minutes, the scout team has played a major role in the Maryland's unbeaten start.
Jared Bernhardt, Anthony DeMaio, Bubba Fairman and Daniel Maltz accounted for all but two of the Terps' goals.
The Terps had two 6-0 runs during Saturday's game.