Manchester United's 1-0 home defeat to West Bromwich Albion was a collective failure, one where Jose Mourinho and almost every one of his players were substandard. As a result, it seems unfair to single anyone out.
What is important, though, is to identify a key area where the team have both advanced and regressed, and this is in relation to United's full-backs.
Ashley Young and Antonio Valencia are two of the squad's most reliable performers, defensively diligent from week to week, but there is a sense that their best instincts have long been suppressed.
This isn't something that can be laid solely -- or even primarily -- at the door of Mourinho, since the issue arose some time before his arrival at Old Trafford. The fact is that two players who were among the very best crossers in the Premier League no longer deliver a consistently excellent final ball.
There are probably a couple of good reasons for that. One is that Young, in particular, has lost some of the speed that allowed him to get clear of his man before delivering the ball into the box. Moreover, he is a right-footer playing on the left wing, and so he always has to check back before he releases the ball.
In some games, the unfortunate and cumulative effect is that United concede a good 10 to 15 yards on the left flank in several attacks, since their opponents know that they will not attack the byline with any great aggression.
The addition of Alexis Sanchez has addressed this issue to some extent, but Sanchez is a right-footer, too, so he also hesitates when cutting inside. This might sound like a small matter, but it is the kind of thing which leads to a greater predictability in United's attack.
Young's loss of attacking flair is partly explained by his growing emphasis on his defensive duties, a fate which appears to have befallen Antonio Valencia.
Valencia's transformation is even more remarkable than Young's -- while Young is widely regarded as a hardworking yet ultimately limited full-back, Valencia has the tools to be the complete right-back. His defending has improved immeasurably and he has the speed and strength to unsettle anyone against him on the flank. He also regularly completes around 90 percent of his passes.
Yet there is a sense that Valencia, though a fine servant -- in so far as such as a concept still exists -- is holding himself back, and has done for some time. During the early part of the decade, he was a regular supplier of superb crosses to the head of Wayne Rooney, providing the striker with so many assists that Rooney scored more goals in a season than he ever had before.
Valencia's crossing is notably less ambitious now, though. Where he once sent accurate high balls into the area, he now drills them low across the box, a lack of loft which often sees them cleared by the first defender.
Spending money on full-backs isn't the only thing Mourinho needs to do to address United's shortcomings -- there's an argument that, at least in Valencia's case, he could be coached a little better.
There were several moments in the West Bromwich Albion game when Valencia received possession from crossfield passes then faced the left-back, who had several yards of space behind him. Yet on almost every occasion, Valencia did not attack that space but waited for a teammate to join him, and both the gap and the moment were gone.
It's this type of conservatism that is holding Valencia and United back. It is confusing to see, especially since Valencia is far more gifted as an attacker than, say, Matteo Darmian.
There's no good reason why Valencia can't be encouraged to take on his man and deliver high balls to either post, especially with Romelu Lukaku -- whose aerial prowess is almost unmatched -- waiting to receive them. In fact, given that the two of them had a preseason to train together, one wonders why this partnership is not more effective.
The struggles of United's full-backs have been just one more subplot of a strangely unsatisfactory season. On reflection, Mourinho was too reluctant to invest in speed down the wings, and too unwilling -- in the case of Luke Shaw -- to use what he already had.
Whether Mourinho will return his gaze to Monaco's Fabinho over the summer remains to be seen, but if United persist with their lack of imagination in wide areas, they are assured of a more unforgiving campaign next season.