Watmore was handed a start by Allardyce at the weekend, after he came off the substitutes’ bench and impressed in the Black Cats’ fixture against Everton a fortnight ago.
The youngster was lively throughout the match against Southampton, but he failed to provide his side with a cutting edge, as they slipped to a 1-0 defeat.
And Allardyce said: “I think he’s got something in his make-up that other players haven’t.
“He likes to try to get in-behind defenders, get in between them and in on goal.
“He’s scored a couple of goals when he’s come on as a sub, and I saw a couple of great runs at Everton.
“I thought let’s see it from the start, let’s see what he’s got.
“He didn’t get any chances, but there were one or two runs which picked up the fans and got us up the other end of the field.
“But then, unfortunately, he didn’t produce any real quality to cause Southampton any problems.”
Sunderland tried to tighten up their defence against Southampton, as they had leaked so many goals in their 6-2 defeat to Everton.
Allardyce packed the midfield for the home match, but that caused Steven Fletcher to look isolated up-front, and they posed little attacking threat.
As a result Sunderland were kept on the back-foot for much of the match, and that didn’t suit Watmore, whose strengths lie in getting forward.
Sunderland’s loss to Southampton has left them down in 19th place in the Premier League table, and they are currently four points away from safety.