Chris Wilder couldn't hide his disappointment after the Blades conceded a late equaliser against Charlton Athletic at The Valley on Saturday.
Mark Duffy gave United a 32nd minute, but three minutes into stoppage time Patrick Bauer prodded home from close range to rescue the Addicks a share of the spoils and despite the Blades now being 15 games unbeaten in Sky Bet League One the Blades boss wasn't happy.
Speaking in the aftermath of the fixture, Wilder acknowledged his side had been made to pay for failing to finish the hosts off and was adamant United should have been leaving the capital with all three points.
He commented: "I expect my team to play well and win, but we've dropped two big points.
"I've let the players off in the last couple of matches, we get the stats and analyse them properly because we're a forward thinking club.
"But the crucial thing is taking your chances, putting the ball in the back of the net and killing teams off and the amount of chances we've not taken in the last three games in frightening.
"This time we've been made to pay against a decent side with some dangerous players, but we've totally dominated the game and for us not to win comfortably is disappointing."
Wilder added: "I'm looking for that relentlessness and ruthless streak in every game, we're a decent side, people recognise that and people know we've move forward quickly, but this is a missed opportunity.
"We could have stuck a marker down at a very good club where we've been backed by over 3,000 of our terrific supporters and for me we've not done enough, we've not seen the game out and that's immensely frustrating."