He's making the case for best January transfer in PL history.
When he was signed United had 34 points through 24 games (1.42/game). Since then they've taken 24 points from 10 games. (2.4/game, 91 point season pace)
Top 4 was basically out, and they were in a dog fight for 5th to get a CL place if the City ban was upheld. Now they're 1 point back of 4th and 2 back of 3rd and based on form they've got a good chance to overtake both of those teams.
(Edit: to be clear I'm talking about impact on *current* season only. VVD obviously has had a bigger impact, but that wasn't till the next season really.)