Rovers at least gave a decent account of themselves and a change of shape and personnel contributed to a much-improved attacking display.
But their problems in both boxes were evident again as they gifted the Chairboys the lead and lacked a killer instinct before conceding a sucker punch second goal late in the game.
Rovers are now seven points adrift of safety following Fleetwood Town’s win at Crewe, staring relegation to League Two full in the face.
“It's a disappointing result but I'm not disappointed with the performance level,” said McSheffrey, who handed starts to Reo Griffiths, Josh Martin, John Bostock and Ollie Younger and switched to a 4-1-4-1 system.
“I thought the lads were good.
“We were creative on the ball and in the second half we created a few good chances and their goalkeeper has had a great game to keep a clean sheet.
“The lads are gutted with the result and they deserved more today.”
Garath McCleary had the freedom of the penalty box to head Wycombe into an 18th minute lead but the play-off chasers did not have it all their own way at Adams Park.
Bostock pulled the strings and Martin linked the midfield with the attack as Rovers registered 17 shots on goal – but ultimately failed to score for a fifth successive game.
Anis Mehmeti then cut inside from the left on 75 minutes and beat Jonathan Mitchell to effectively settle the contest.
McSheffrey said: “Wycombe are relentless in what they do, getting crosses into the box, winning headers all over the pitch. It's hard to stop.
“They had the territory advantage in the first half - they had corners, set plays and lots of crosses into the box and we've defended it really well.
“I thought we dominated the game for a good 20 minutes in the second half.
“Their goalkeeper has made a few great saves and we feel we should've got it back to 1-1 and then we've been hit with a counter.
“The performance level was good though and I’ve reiterated that to the boys. That’s the standard we expect.
“That performance level has to be the benchmark. We have to match that next week.
“We have to be courageous, take the ball, play our football and just add that little bit more killer instinct.”