The Parkhead giants suffered another setback in their bid to win an unprecedented 10th consecutive league title on Sunday afternoon, drawing 1-1 with St. Johnstone.
The result left the Bhoys 13 points adrift of Rangers at the summit of the Scottish Premiership, with Lennon’s side also dumped out of the Europa League and League Cup in recent weeks.
But MacLeod, who won a cup and league double during his time alongside Wim Jansen in the dugout, believes that the Northern Irishman’s squad must shoulder their fair share of blame of his side’s recent slump.
Speaking to Sky Sports News, he said: “Neil’s the one that’s been getting all the stick.
"The players have got to take a look at themselves – every single one of them. Just look and say, ‘Look in the mirror. What am I not doing that I used to do last season?’.
"Even a lot of the new players… I always felt, when you're bringing new players into the club, they’ve got to be better than the players that are already at the club. I think this season, that’s not happened.”
MacLeod also argued that Lennon could buy himself valuable time to steady the ship at Parkhead if he wins last season’s Scottish Cup against Hearts later this month.
"If you’re still at the club, and you win the Scottish Cup, you can’t sack a manager who’s just won the Cup”, he said.
"They’ve got to keep on going. Hopefully by then Celtic are on a run.”