The way I interpreted the whole saga was Suso was in charge of recruitment and worked with Dean and the other coaches on what positions they needed strengthening, what attributes they were looking for in a player etc.
To my eyes, Dean had very little to do with scouting and signing players last season. Certain players looked like DS choice, Jota and Konsa, possibly Drinkwater, but I think all of the belgian/turkish/french league no names were Suso signings and the failure of these players last season led to his sacking by Purslow.
Smith came out after the Suso sacking and said he never had any problems with him, enjoyed working with him etc. Suso was sacked because he was incompetent at this level, and arguably at championship level too (Kalinic etc).
Last summer was 100% DS, Lange wasnt around long enough to sign anyone and they were hardly going to sign anyone off the back of Suso's work after sacking him.
I think this is Lange's first window, but I wouldn't be surprised if, like Deano said above, DS has far more of a say from here on out after the success of summer transfers and the raging success of a season he's having.