I watched Simms a lot last season at Hearts and while he was great for us, I think he is probably a Championship level striker in all honesty. Would love to be proved wrong.
His main strength was pace and power. He was able to bully SPFL players quite easily but EPL is a different beast in that regard. His touch wasn’t great and for a big guy he didn’t win a lot in the air (in fact for all his goals I don’t remember him scoring a header).
All of that said he had decent showings against Celtic and Rangers (probably mid level EPL equivalent) and has to be better than Rondon.