Manchester United failed to score against relegation-threatened West Brom, and in turn, handed their bitter rivals Manchester City, the Premier League title.
Vidic analysed his former club's performance on 'Sky Sports' following the match and particularly noted United's worrying lack of pace in their game.
He said: ''Today they didn't show what we expected, the energy going forward, that burst or sprint. It was too slow, which was disappointing. That is my worry. I'd like to see United playing faster, quicker with the ball.''
The former defender added: ''They didn't move well without the ball, they didn't move fast. The players didn't perform the way they wanted. It's sad to see Man United lose at home to West Brom, a team who have won just three games all season.''
Vidic also noted that the FA Cup semi-final against Tottenham is fast approaching, and he had concerns over the mentality of the players.
He said: ''It hurts, because United need a good spirit ahead of the Tottenham match, an important match. It seems like he is saying there is a problem with mentality in the players. You play for Man United, it's not acceptable to draw or lose, always you have a high expectancy.''