The 36-year-old appeared to struggle with Emery's new approach of playing the ball out from defence in Sunday's season opener, nearly scoring an own goal in the 2-0 defeat as he looked uncomfortable in possession.
New Gunners boss Unai Emery opted to keep the £56 million signing on the bench as he preferred Pierre-Emerick Aubameyang to lead the line in a 4-2-3-1 formation for the North Londoners against defending champions Manchester City.
'Leno is starting with us and he is working very well and played very good in pre-season.
"It's very naive at the moment; you've got to put it into practice first", McMahon told Sky Sports' The Debate.
According to reports in the Star, Unai Emery is unhappy with the weight of some of his players in the Arsenal squad and believes they are "too fat".
Arsenal has been handed a major boost after Nacho Monreal and Danny Welbeck returned to full training. "But if (in future) Bernd starts, I believe in him also". Years of management under Wenger had left the players seemingly terrified of their own shadows, abundantly aware that even the most minor error would result in condemnation from supporters and the media. "We still need some time to adapt to the new manager and to integrate the new players", he added. Mendy carried the ball forward from inside his own half, played a one-two with Sterling on the left wing, got to the byline and cut the ball back for Bernardo Silva, who fired the ball into the net.