The 20-year-old, Tammy Abraham scored 26 goals in 48 appearances during his loan spell with Bristol City last season and has found the net five times in 10 games for Swansea City this term.
Michy Batshuayi struggled to impress in Alvaro Morata’s absence when the Spaniard was sidelined with a hamstring injury earlier this month.
And Lampard feels his former club should have kept hold of Abraham as an alternative option to Morata.
‘For Chelsea as a club, yes it is a mistake,’ Lampard told BT Sport. ‘It’s not [a mistake] for Tammy as I don’t think he would have played so many games.
Now you see him playing regularly and he is improving as a player.
‘Chelsea could say ‘we didn’t feel Tammy was going to play’, if you say Morata was fit all season then it is great experience for him and he comes back next season as a well-rounded player.
‘But now Morata is injured it seems a mistake. You can’t have it both ways. I know I’ve sat on the fence there but you improve the individual by sending him on loan, but as a club now you go ‘maybe we could have kept him’.’