The Anglo-Nigerian striker scored 26 goals in 48 appearances for Bristol City in the English Championship last season and already has four Premier League goals in eight games played so far for the Liberty Stadium outfit.
And with Michy Batshuayi not proving a worthy deputy for Alvaro Morata, the ex-England international believes the Blues have made an error in loaning out Abraham but also highlighted he understood the logic behind the move.
“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 a 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’,” he concluded.
Abraham will be looking to add more goals to his tally when Swansea host Leicester City in their next game on Saturday.