Assuming the half player he's referring to is the bloke we signed last summer.
Personally I think he's underplaying how effective Herrera will be in the Premier League. Herrera's style might be too English for La Liga but his willingness to run from midfield and commit players will stand out for us. Especially as we've had nobody to take the ball forward from midfield that since Ando stopped progressing. I don't see Herrera being a Carrick style unsung hero, he's too dynamic and too mobile for that. Rafa Hernandez is right that Herrera's probably not going to be an assist machine, he's not a Modric or a Xavi. However, Herrera's got the engine to drive us forward, he won't just stand their waiting and pass it sideways if there's no obvious ball on. Herrera will take responsibility for putting us on the front foot, and we like that kind of midfielder in England (look at the love Ramires gets!) Herrera will be the darling of both the United faithful and the Manchester press pack in no time.