"We're in a little bit of a rut here and it's tough," said Rahe, whose team still has a chance for a first-round bye in the upcoming Big Sky tourney if it can beat Montana State on Saturday.
The top four teams in the regular season receive byes past the first round of the conference tournament.
Montana (15-16, 11-7) trailed 66-56 at the Dee Events Center after Senglin canned a pair of free throws with seven minutes left.
But it was the play of Grizzlies guards Ahmaad Rorie and Sayeed Pridgett that dominated the next three minutes as Montana registered a 13-2 run to go ahead 69-68. In that stretch, Rorie made a pair of threes while Pridgett tallied five points.
"They just put their heads down and decided to go at us," said Rahe of the Grizzlies backcourt players.
Trailing by one, 73-72 approaching a minute to go, Weber State extended Montana to the end of the shot clock before Rorie rebounded his own miss and reset the play clock. Given a second chance, Rorie this time dished off to Michael Oguine for a dagger 3-pointer and a 76-72 lead with 55 seconds left.
"I feel like other teams have been getting a lot of offensive rebounds, especially at the end of games," said Weber freshman Jerrick Harding, who finished with 17 points. "We can't get stops down the stretch, and I feel like that's been our biggest problem."
Senglin ended with 22 to lead the Wildcats and has consistently been the team's best option for a last-second shot. It didn't happen against Montana, though. After a miss by Rorie with 16 seconds left kept the score at 76-74, Senglin raced into the lane for a try to tie.
But Senglin bumped against a teammate and the Grizzlies tied up the ball. With the possession arrow in favor of Montana, the visitors got the ball back with 1.5 seconds remaining and Walter Wright made a pair of free throws for the final margin.
"I ran into one of my teammates. It was my fault," Senglin said. "I picked it up and [a Montana player] got his hands on the ball. Couldn't get the shot up."
Senglin's output put him one point ahead of Damian Lillard for second on the all-time Weber State career scoring list.
But the points have been tougher to get late in the season for Senglin and the rest of the Wildcats, according to Rahe.
"Teams have really figured out how to play us now, which they didn't the first ten games," Rahe said. "They changed their style of play and it's affected us. They're really pressuring and really denying, especially Jeremy, and they're not allowing us to shoot threes.
"First ten games of the season, we were allowed pretty much to shoot anything," Rahe said. "All of a sudden, you're scouted and some of your deficiencies show up."