With returning boss Steve Cotterill watching on from the stands at Montgomery Waters Meadow for the first time in more than four months, Town gave up a 2-1 lead in the second half to the U's, who kept their play-off hopes alive with the win.
Elliot Lee scored early for Oxford before first-half efforts from Matthew Pennington and Josh Vela had Shrews in a deserved half-time lead in front of their returning boss.
But Oxford came on strong after the hour mark and James Henry and Dan Agyei struck for a crucial three points. Wilbraham, who received instructions loud and clear from Cotterill at the back of the main stand, believes the advantage of a free week for Oxford, while Shrews lost at home to Lincoln on Tuesday, was telling late on.
He said: "It's hard to take but I thought the lads were excellent today. From start to finish they gave everything.
"The manager being here gave them a massive lift, from 70 minutes onwards you could see they'd had a clear week and we'd had a midweek game, that was massively evident.
"We just didn't have the legs to keep going, the workload has been relentless and the manager was really pleased with the energy they put in.
"The manager enjoyed seeing the boys again and was really pleased with the effort."
Wilbraham added: "The lads showed really good character, they didn't let the goal against affect them, as the manager always says. If we'd have a clear week we'd have seen that game out, definitely.
"It's not making excuses. You could see the lads were still giving everything but didn't have much left in the tank. The Oxford lads looked a lot fresher legged than us at the end."
One of the afternoon's major positives, along with the return of the manager, was the performance of Tom Bloxham on the 17-year-old academy starlet's full debut.
Switching between a mixture of the wide right and forward role, Bloxham – a rangy 6ft 5ins former Leicester youngster – occupied the U's defence and caused problems all afternoon before cramping up after the break.
Wilbraham said: "I thought he was unbelievable, all that was missing was a goal, what a debut.
"He hardly lost a header, he occupied their centre-halves, two big lads, their bench were constantly praising him, asking how old he was, (saying) 'is he only 17?'
"All their coaches made a point of going over to him after the game, I thought he was unbelievable. He led the line and was the one driving the game in the first half."