The former Man United defender also discussed the loaning out of Adnan Januzaj but particularly focused on the decision to let the young forward go a year ago.
Indeed, Neville saw selling Welbeck to Arsenal as a red flag at the time and it still bothers him to this day.
Neville told the Telegraph: "I am still saddened that Danny Welbeck left. I am saddened that Adnan Januzaj has been allowed to leave on loan to Borussia Dortmund.
"It was an early red flag to me when Welbeck was sold for £16million, as I said at the time. Januzaj went from playing four or five games on the bounce to going out on loan in Europe."
Since leaving Manchester United, of course, the 24-year-old hasn't arguably progressed any further. Certainly not as much as he would have hoped.
Welbeck's current problems are injury related but, since joining Arsenal, the forward simply hasn't made enough of an impact up front. Both goals and game time as a centre-forward have been rare for Welbeck with the Gunners, although he has shown better form in the final third with England.
Manchester United could certainly have done with another forward, though, and now have the expensive but younger Anthony Martial taking up the role Welbeck will have done at Old Trafford in the past.