In trying to fix the minefield that has been Manchester United's midfield this season there has been an endless combination of systems and players and a growing weariness that this is an issue that can only be fixed through cash.
As the campaign has gone on the decision not to sign a central midfielder last summer has looked more and more costly, but through all of the tinkering, there has been a reluctance to try Scott McTominay in a holding midfield role.
The academy graduate is never deployed without a midfield chaperone alongside him. That can give him licence to get forward and he can score goals, but he also has the attributes to become a defensive midfielder and that is where the gap is for United at the moment.
It has taken until mid-January for United to move to a 4-3-3 that Ole Gunnar Solskjaer had earmarked for them back in July and while the performances at Aston Villa and Brentford have had their imperfections, the balance in midfield has finally looked better.
The key difference between the game in the Midlands and last night's at the Brentford Community Stadium was the sight of McTominay restored to the side in place of Nemanja Matic - and playing the exact some role.
It can feel like a combination of the two might give United their ideal holding midfielder. Matic has the positional qualities, discipline and experience to play the role. McTominay has the physical qualities to do it.
The concern with playing the Scot in that role is his eagerness to get on the front foot and whether he can show the patience to hold his position in front of the defence. That will only come with time, but against the Bees, he showed enough to think he can have a future in that position.
McTominay will pick over the tape of a ragged first-half from everyone in United's electric blue and yellow, but he more than anyone helped Rangnick's team get a grip of the game after the break. He showed the flawed value of assists in failing to collect one but playing the most important role in the second and third goals.
Those moments highlighted the aggression and forward-thinking that would delight Rangnick. First, McTominay snapped at the heels of Bryan Mbuemo to win the ball midway inside his own half, near the right touchline, and having regained possession he clipped a pass into Cristiano Ronaldo, who chested the ball onto Bruno Fernandes and United were suddenly through on goal.
Fifteen minutes later McTominay was in a central position to throw a long leg in front of Yoanne Wissa. Having won the ball he darted through the middle and laid it off to Fernandes. Again United were clear. The Portuguese set up Mason Greenwood for the second goal and Marcus Rashford for the third, but it was McTominay who deserved so much of the credit.
Those moments showed he has what it takes to play as a holding midfielder. He is still young enough to learn the position and to be a key player for United for years to come. Rangnick's 4-3-3 should be here to stay and McTominay should be keeping that role.
Whether he can hold it down beyond this summer is up for debate. United will be in the market for a world-class defensive midfielder and McTominay could go back to being a squad asset. A significant one, at that. He might not be the first choice for that role, but it shows United don't need to break the bank on two holding midfielders.
Every competitive squad needs depth and McTominay has proved he can be a reliable performer at the base of midfield. His contribution wasn't lost on the away end, who belted his name out at the final whistle. The conundrum is how it's taken so long for this combination of midfielders to be used in this system, given it has also produced better displays from Fred and Fernandes. United have a template going forward.
