But UCI's first 20-win season in 10 years isn't over yet, as the Anteaters (20-15) will compete in the CollegeInsider.com Postseason Tournament.
UCI will be on the road in its first postseason competition since the NIT in 2002. UCI Coach Russell Turner said his team will play either Tuesday or Wednesday against an opponent to be determined.
"It's a great opportunity for our guys to have another chance to play," said Turner, who was hoping that that chance would be in the NCAA Tournament, in which UCI has yet to compete.
It was UCI's fourth loss in a Big West Conference Tournament final, to a fourth different team.
It was Pacific (22-12) that pounced on the 'Eaters early this time. After Pacific scored the first four points of the game, the two teams exchanged leads, until a 9-0 run by the Tigers opened a 26-14 advantage with 6:17 left in the first half.
UOP, which capped its final season in the Big West with the program's fifth conference tournament crown, led, 31-20, at halftime.
But UCI, which split its two regular-season meetings with Pacific, mounted a comeback midway through the final half.
The Anteaters, who came in having won eight of their last nine and had won 15 of 16 previous games played in Orange County this season, pared a 38-25 deficit to 42-39 with 11:33 left.
Senior Daman Starring, hit the last of his three second-half three-pointers to cap a 14-4 run that sent a surge of energy through a large UCI cheering contingent that made up about half of the 6,795 in attendance.
But after a Chris McNealy put-back made it 44-41, the Tigers went on a 5-1 run and drained 14 of 18 foul shots in the final 10:22 to head off to the Dance.
Starring scored 15 of his team-best 19 points in the second half and finished six of 12 from the field. He was the only Anteater to shoot at least 50%, as UCI finished at 35.8% from the field, including six of 25 from three-point range (24%). UCI was one for 10 from threedom in the opening half.
McNealy had 12 points and a team-leading four assists, while senior Mike Wilder had nine points, five rebounds and three assists and sophomore Will Davis chipped in eight points, six boards and two blocked shots.
Senior Adam Folker, who had missed the previous four games with a knee injury, had two points, and six rebounds in 12 minutes off the bench.
Pacific (22-12), will take a seven-game winning streak into its ninth NCAA Tournament appearance.
It was Thomason's fourth Big West Tournament championship in 25 seasons at the Tigers' helm.
"I'm proud of this group of guys, especially our seniors," Turner said. "They fought and were fearless. But Pacific made more plays than we did and they should get credit of winning tonight."
Said Thomason: "It was a good thing for us that Irvine wasn't on its three-point shooting tonight, because if they are on, we could not have guarded them tonight."
Davis, Young and Starring were all-tournament picks for UCI.
Pacific's Tony Gill, who had 19 points Saturday and 39 in the last two wins, was named MVP.