When Wan-Bissaka was recalled against Burnley and Wolves either side of New Year's Eve, his inclusion was incongruous. His second season was subdued and the third has been sub-standard.
It is not a coincidence Wan-Bissaka, one of the poster boys of United's recruitment reboot and 'cultural reset' of 2019, has lost his place since Ole Gunnar Solskjaer was sacked. The hand injury he sustained at Chelsea in Michael Carrick's second game in caretaker charge was serious enough for him to miss the 3-2 win over Arsenal and he has started three times under Ralf Rangnick.
Wan-Bissaka was carried off at the end of the meaningless match with Young Boys and absent through illness for three successive matches last month. Before the minor hand injury, he had not succumbed to an ailment or injury all season.
It was only 17 months ago Diogo Dalot was such an irrelevance Timothy Fosu-Mensah started ahead of him at left-back at Crystal Palace. Dalot has lined up in United's last eight games and in 11 of the last 14.
The Portuguese has performed consistently during his run, bar an aberration at Villa Park, and benefited from undertaking a catenaccio course during his gap year in Milan. Dalot's attacking output has, however, been disappointing and he is without an assist all season. Dalot overhits crosses and Wan-Bissaka underhits them.
United may be relieved Kieran Trippier, an all-action full-back who specialises at set-pieces who they targeted in the summer, has had his transformative effect at Newcastle curtailed by a broken metatarsal.
Dalot turns 23 next month and Wan-Bissaka turns 25 midway through next season. The latter is in danger of becoming an expensive write-off and the next manager has to be decisive, with Dalot out of contract next year and Wan-Bissaka in 2024. United have one-year extension options with both.
The Neville brothers recommended Joao Cancelo to United in 2017, one of the few Valencia players to leave an impression during Gary's disastrous tenure. Yet the timing was not ideal. Antonio Valencia was United's standout player in 2016-17, Matteo Darmian secured his future with an uncompromising performance in the Europa League final, while Luke Shaw and Ashley Young were sidelined with long-term injuries, so neither could be shifted to make room.
To pigeonhole Cancelo, Trent Alexander-Arnold and Reece James as full-backs does them a disservice when their impacts are more comparable to that of a playmaker. Cancelo and Alexander-Arnold are certain inclusions in the Premier League team of the year.
United have assembled a respectable quartet of full-backs with England, Brazil and Portugal internationals but football is so ever-changing and unforgiving clubs can quickly get left behind and United are prone to standing still. In the summer Cancelo was put forward, City signed Danilo from Real Madrid and quickly became vexed by coverage they had recruited another right-back weeks after the record arrival of Kyle Walker for £50m.
City were adamant Danilo was a right-back and a left-back. When introduced to reporters in Los Angeles, the only English words Danilo spoke were 'right-back'. Danilo played 18 times on the left before City upgraded him for Cancelo in a swap deal in 2019.
United need a full-back in Cancelo's mould, even if he is the rarest of finds. Trippier, adept on the left, fit the bill despite his short shelf life. Brandon Williams is developing encouragingly at Norwich, though nobody is pretending he has a ceiling as high as the classy Cancelo's.
Dalot and Telles are far from assured of squad places at the winter World Cup and if United are to enhance their full-back department someone has to make way in the summer. Tariq Lamptey came up against Williams in the FA Youth Cup in 2018 and was showered with compliments by United in midweek when Shaw cynically fouled him before Rangnick introduced Telles for Jadon Sancho to protect Shaw.
Lamptey has played solely down the right for Brighton but is only 21 and has already caught the eye of Antonio Conte. At this rate, Conte could become available to United in the summer to herald another transition at right-back.