Derby County strengthened their squad successfully during the summer but failed to seriously improve one key position. Derby captured 12 new players to prepare for the Championship, with a transfer for goalkeeper Jacob Widell Zetterstrom arguably the Ram’s biggest bargain. Zetterstrom has inspired his defence to three home clean sheets in the second tier as Paul Warne’s men maintained a 100% home record at Pride Park. Warne was also able to bolster his midfield this summer, as Ebou Adams, Ben Osborn, David Ozoh and Kenzo Goudmijn have also flourished at the start of this season. However, the D…