You can't really give much credence to these straight-up stats comparisons.
Martinelli's end product would change dramatically if we made tactical changes that suited his game more. And if Williams came here and Martinelli had a bad run and got dropped, we'd get to see what Williams is made of.
I say that as someone who's sceptical that Martinelli's easy to upgrade.
If we want to strengthen our current attack, we'll need a leap of faith and insight. One of Martinelli, Havertz or Saka would be being upgraded, and everything rationally says all three are very hard to improve on, even if most would say Gabi is the easiest.
There's no guarantee signing Gyökeres or Šeško improves on anyone we have for example.