Billed as a good opportunity for United to cut the gap between themselves and the Cherries before kick-off, instead it highlighted the gulf between the two sides as the Blades fell four points behind fourth-bottom Luton Town in the race for survival. A chorus of boos rang around Bramall Lane at the final whistle and were fully justified on an afternoon to forget for all involved.
United must pick themselves up quickly ahead of another seismic clash against bottom club Burnley at Turf Moor next weekend, where another poor performance or negative result will only increase the pressure on boss Paul Heckingbottom. Here are eight things we learned from the Bournemouth defeat...
1. A blow to belief
After four points from two games, and then Everton's points deduction, the international break brought some rare positivity in United's season which, over the course of 100 or so painful minutes against Bournemouth, evaporated. Bournemouth kicked off two places and four points above United but the gulf between the sides was seismic, from the first whistle to the last. United couldn't seem to string two passes together, they gave the quiet home crowd nothing to get excited about and two shots on target - one minutes from time and the other Oli McBurnie's consolation goal - tells its own story. The performance, more than the result, has prompted fresh doubts on the terraces over United's chances of surviving in the Premier League and it wouldn't be the biggest surprise if they began to creep into the dressing room as well. But somehow United's players have to retain their own belief and can right some wrongs next weekend at Burnley.
2. The worst this season?
It's a big call to make in a campaign that has already seen United hammered 5-0 and 8-0, on their own turf. But there is a strong argument that United's display against Bournemouth was their worst of the season so far. At least against Newcastle and Arsenal there were some vague mitigating circumstances - both sides are in the Champions League and United at least had a spell in the game before the Magpies took control. This was against a fellow side battling for survival, rather than trophies, and United barely had a kick. If they could not cope with a fellow member of the four-team mini-league of relegation battlers (which became five thanks to Everton's points deduction), what does that say about their chances against the rest of the division? Football doesn't work as simply as that, of course, but this felt like a big opportunity missed.
3. Team selection
Many, myself included, expected McBurnie and Anel Ahmedhodzic to start after returning from injury but both only made the bench from the start. The pair were disappointed not to make the starting line-up but as McBurnie admitted afterwards, can have no complaints because they were "miles off it". McBurnie showed classic signs of ring-rust, his touch evading him a couple of times before his late well-placed header cut the deficit, while Ahmedhodzic was caught ball-watching as Marcus Tavernier stole in to make it 3-0 from close range. But, looking at the positives, the return of both men does strengthen the options at Heckingbottom's disposal while striker Will Osula gave the manager some more welcome food for thought with a bright cameo which was one of the few positives from a United perspective.
4. More questions over Hecky's future
They were somewhat inevitable after a performance like this and will only increase in volume and velocity if his side don't bounce back with victory at Burnley this weekend. Heckingbottom didn't deviate from his previous answers about his future - reminding that the decision is down to owner Prince Abdullah, rather than himself or the club's supporters - but the boos that rang around Bramall Lane at full-time will surely have reached Riyadh or Los Angeles, where owner Prince Abdullah was busy tweeting about Al Hilal's 9-0 win over Al Hazem. "Nothing's going to change in terms of how hard I work and what I work with," Heckingbottom said. "I say it all the time; until someone tells me differently, we'll continue working as hard as we can with what we've got. As a group of staff and players. And that won't change."