Strikers at top 6 clubs:
Morata - Technically strong, big game winner, above average if not world class.
Gabriel Jesus/Aguero - Jesus is technically sound again and links up well with his teammates. Like Morata, he is above average with room for development. While Aguero is well-known to be world class, though on the wane.
Lacazette- By far the weakest of the rival strikers, but again, he shows good understanding with Sanchez and Ozil.
Spurs - The Harry Kane Team.
Liverpool - Firmino is the second best striker in the league after Kane. Goal-scorer, prolific creator whose presence helps Salah and Mane or Coutinho as well. A truly elite striker who is often underrated, as he is very unique in elevating the levels of his teammates. In fact, I'd sooner have a striker like him playing for us than even Kane, Liverpool unearthed a gem in him and Salah.
Compare these to Lukaku and you will see the cause for concern.
I'm concerned with his form rather than his ability. The whole team is struggling at the minute. He's more than capable of scoring 20 more goals before the season is up.