The ex-Celtic boss has been reflecting on the Scottish champions selling the 'crown jewels.'
The Bhoys sold the likes of Victor Wanyama, Gary Hooper, Fraser Forster and more while Lennon was in charge and the 43-year-old admits it is 'very difficult' to keep producing players that meet the right standards at Celtic Park.
And, due to a lack of finances, Lennon believes the Scottish game as a whole is significantly weaker. That, in turn, weakens Scottish sides' ability in Europe.
Lennon left Celtic last summer and is now in charge of Championship side Bolton Wanderers, with Norwegian Ronny Deila having replaced him at Parkhead.
“It all depends on Celtic,” he said. “When I was there we ended up selling the crown jewels in terms of Victor Wanyama, Gary Hooper, Fraser Forster, Joe Ledley, Georgios Samaras.
“It’s very difficult to keep churning out those players but that was the financial situation. There’s no doubt the Scottish game is significantly weaker - Hibs, Hearts and Rangers are in the Championship and they were a big loss in terms of revenue, crowds, quality and competition.
“It’s lacking at the minute, it’s not in a great state. There’s seven or eight teams in in the Premiership who have average gates of 4-5,000 and with that it’s very difficult to compete with other European countries.”
Celtic face St Mirren in their first game back after the international break, already holding a five-point lead over second-placed Aberdeen.
The Bhoys have wrapped up the Scottish League Cup this season and face Inverness Caledonian Thistle in the Scottish Cup semi-final. Deila's men also reached the last 16 of the Europa League and were narrowly knocked out by Inter Milan.
Despite that, though, Lennon's claims certainly seem to stand to reason...