The U’s have typically played a 4-3-3 system under Buckingham, with two attacking midfielders pushed in advance of one holder in the centre of the park.
The wingers are key to the set-up, remaining high and wide, with the full backs tending to play a more reserved role.
However, injuries to four wide players in Siriki Dembele, Kyle Edwards, Matt Phillips and Przemyslaw Placheta, have limited Buckingham’s options on the flanks.
Time for a change of shape? The key talking points from Sunderland defeat
Talk of a change in shape had been discussed prior to United’s trip to Sky Bet Championship leaders Sunderland, and although the U’s started with a 4-3-3, a switch at half-time saw that become a 3-5-2 set-up.
Greg Leigh replaced Idris El Mizouni, with Peter Kioso and Leigh providing the width from wing back.
Leigh, who was outstanding when Liam Manning utilised wing backs in the early stages of last season, was in particular a useful outlet at the Stadium of Light.
Elsewhere, Tyler Goodrham and Ruben Rodrigues joined Will Vaulks in midfield, while Mark Harris partnered Dane Scarlett up front.
Buckingham said: “We’re missing seven, if not eight first team players, four of which are wingers. We’ve seen the importance of those wide players to the way we want to play in our formation.
“We tried something in the first half with Mark Harris playing outside Dane, who’d scored two in two.
“At half-time, we felt they were getting a lot of success out wide, so we just flipped formation to a five.
“It’s something we will need to work on because whether we start like that or flip to that, we need to become as comfortable as we are playing the other way, especially when we’re missing four of our wingers.”
He added: “Whether it’s 3-4-3 or 3-5-2, it’s one thing saying a formation, but it’s another how you want to play within that formation.
“It’s not just with the ball, it’s how you press, how you sit in block, it’s what you want to do from a low build, and then when you get into midfield and the final third, there’s a lot to it.
“Leading into this game, we had one day on the training pitch and there was a temptation to maybe flip the formation, but with the amount of detail we’d need to get into, I just felt it wasn’t the right way to start against a team that are where they are.
“What we do know is we’ve got a full week leading into the next game, so it gives us the opportunity and choice if we want to do that, to take our time to get it right.”