Michigan State has been finding ways to win lately, even without playing well.
The Spartans played well, but took its first Big Ten loss in a battle with in-state rival Michigan 80-75 at Breslin Center.
"You never want to lose and we forgot what it tasted like because we've been winning even when we played bad," Costello said. "To lose, it puts that bad taste and it hurts even more because it's Michigan."
Coach Tom Izzo didn't hide his feelings on the loss – he corrected a postgame question from "disappointed to "crushed" – but the pride he felt for his team was most evident.
"In 30 years I've been here, I've never been more proud of a team," he said.
His postgame message to his team was just that: Pride – even if it fell on upset ears.
"He was incredibly proud of us," Russell Byrd said. "I think everybody was proud of everybody. That's kind of the bright side of all of this, but still we didn't get the win so it's a little disappointing."
Gary Harris had a career-high 27 points, but it was the efforts of freshman Alvin Ellis with 12 points, Costello with nine rebounds and nine points and big minutes from Gavin Schilling and Byrd that gave Izzo a sense of pride.
"Just how hard we worked," Costello said. "We were down two guys and we played pretty well. I'm not saying we played our best, but we played pretty well.
"We just didn't finish the game."
Falling behind early 10-2 behind a 4 of 4 shooting start, they went on a 19-6 run to take control early 21-16 before having a 36-30 halftime lead.
It was a lead they held until Michigan center Jon Horford tipped in a missed free throw with 7:14 to go to give Michigan a 55-54 advantage – its first since it led 16-14 with 11:58 left in the first half.
MSU quickly regained the lead, but after a 60-60 tie with 4:01 left, it was all Michigan. Freshman point guard Derrick Walton scored 10 of his 19 points in the final four minutes to lead the Wolverines, which also received 19 points from Nik Stauskas and 17 from Caris LeVert.
The Spartans pulled back within one possession after Keith Appling hit a pair of free throws with 10 seconds left, but that was it as LeVert hit two to seal it.
The efforts of Appling might have instilled the most pride in the Spartans' coach. Appling admitted after the game he can't shoot right now because of a wrist injury, but played through it.
"Coach saw that and that's why he was (so proud)," Costello said. "Everybody else did their job and played hard, but Keith put his heart on the line for us. We just didn't finish the game for him."
The loss gave Michigan possession of first place in the conference and dropped the Spartans to 6-1 in Big Ten play and 18-2 overall.
"We are still right in this hunt," Izzo said. "Don't kid yourself. We're here and we might even be stronger than we were before the game.
"We've gotta find a way to survive."