Fergie says that the Dutchman has improved the whole of United's attack since he joined the club from Arsenal.
Van Persie himself has netted his far share of goals also since his arrival; he is already on 15 for the season so far.
The United boss told Yahoo Sport: "The attacking aspect of our game has definitely improved (since van Persie joined) and of course he has weighed in with 14 goals (before the 3-1 win over Sunderland) so far.
"Chicharito has got nine goals, Rooney has seven I think and we have scored around 43 goals as team, which is quite a high amount for this time of year."
Source: United Mad