The young Spurs forward joined the Championship outfit on a season-long loan this summer.
He was handed his Ipswich debut against Fulham in the EFL Cup and on Tuesday he came on as a 71st minute substitute, replacing George Hirst, against Saints.
McKenna insisted that Scarlett did a very good job in a pressure situation and tough environment against the Saints’ defence in the final 27 minutes of the hard-fought Tractor Boys win.
“Of course, then Dane coming on as well”, McKenna told Ipswich’s media.
“You know for 25, 30 minutes whatever was it with the extra time in that pressure in that environment and against those centre-backs.
“You know that’s great for him and that helps integrate him into the group.”
Tottenham will keep a close eye on how much game time McKenna hands Scarlett as they look for him to clock regular game time and continue his development.