Reus has gotten worse? He had a rotten last year in terms of injuries, but in normal form he has clearly improved over the last years. His passing game, vision and creativity have clearly improved. In general he took over more duties in terms of play making after Götze left and is now more wellrounded than in his last years at Gladbach or first years at Dortmund.
In terms of scoring ability, Reus should in theory at least match Bale´s numbers. Both had a similar score/minute ratio (low 70 area) in their peak seasons, but the problem with these kind of comparisions is that it ignores tactical setup of their own teams (Bale being the undisputed main man at Spurs compared to Reus playing alongside top class striker Lewandowski) and the opposing teams (way more defensive vs. Dortmund compared to Spurs).