The midfielder also rued the schoolboy error which saw them concede a quick equaliser in the 1-1 draw with Leicester.
Spurs are so far winless in the Premier League, with them being beaten by Manchester United on the opening day and having drawn their other two games against Leicester and Stoke, both of which they were leading.
And their midfielder believes they are lacking the cutting edge to kill off games, having yet again let a lead slip against the Foxes as they did against Stoke the week before.
"I think we're missing that cutting edge at the minute, we've gone one nil up today and blew a lead," he told Sky Sports.
"Last week we did the same, we've not been playing badly but we need to learn to see out a game quickly and get a win."
It will be the failure to hold a lead that is most concerning for manager Mauricio Pochettino and something he will be keen to rectify as soon as possible.
With the addition of Toby Alderweireld in particular the Argentine will have thought he had strengthened his defence this summer. But conceding two at home to Stoke and a quick equaliser against the Foxes at the King Power will surely have changed his mind.
Tottenham had taken the lead through Dele Alli’s 81st minute goal but Leicester equalised a minute later when Riyad Mahrez leveled the scores. And Mason was disappointed, labeling it a schoolboy error to concede so quickly.
"I think it's a schoolboy error," he added. "You go one nil up away from home and to concede so quickly is disappointing."
Hardly rocket science from the 24-year-old - but what does he plan to do about it?