Why?
I actually think he's been one of the best signings in the January transfer window.
He wasn't bought for his goalscoring. Utd aren't short in that department. They seem to score all over the pitch, especially with Rashford in the form of his life.
Weghorst was bought as a striker to cover Martial (when injured) and who can press and so far he's been a pressing machine for Utd. He's actually been underrated for Utd by the press and pundits.
He's not a glamour name and he doesn't possess the best scoring stats, but he certainly helps their attack.
He's basically doing what Giroud for France has done.
No doubt Utd will spend big in that department come the summer, but Weghorst has certainly done a good job for them so far.