In fact going to that finishing point, pretty sure Costa didn't score a single goal from outside the box for Chelsea until this season, which probably explains his pretty astonishing finishing rate.
Mario Gómez has made an entire career out of scoring high percentage shots and doing nothing else as well. That then must go to chance creation, which goes to the point that Mourinho's style of play means that it is harder to create high percentage shots (other than counter attacking, which again is harder with Ibrahimovic in the side and is against teams that decide to give you space in behind i.e. poorly organised defensive teams). The fullback things also has generally been an issue in Mourinho teams, it's not even just having a fullback that pushes beyond and creates space(Ivanovic did that all the time for us but was still useless other than set piece threat) it's also having dynamic fullbacks who have the ability to actually damage you with the extra space that they create, which is often the reason why nowadays fullbacks are often failed wingers instead of centre backs. Mourinho tends to use one of these instead of two which probably ties in to why Shaw isn't playing(plus any animosity/vanity issues he clearly has with the player).
I can see why Pep uses Navas at RB and there is no coincidence that SAF/Van Gaal/Moyes and Mourinho thought Valencia was a viable option at RB? Moses too. Even Marcelo used to play at LW under Pellegrini yet got moved back under Mourinho. Nowadays the winger/fullback connection seems to be very important, so having a fullback that has played as a winger makes it easier, the positioning aspect can always be covered by a defensive midfielder and these fullbacks tend to be very fast so it means they can use their recovery pace as a last resort when they're caught out of position. Probably why Fernandinho and Delph started today coming to think of it.