I can sort of understand the logic. Cowboy is super brittle and stiff on the feet these days, while Paddy has shown durability and power despite his total lack of defensive responsibility. I think he would get touched up, but get through with big punches and ultimately take Cerrone out if Cowboy kept it standing.
Conversely Donald is and always has been slept on by many for his BJJ and offensive wrestling skills. Donald has an insanely good guard and is a lethal finisher on the mat. Recently he has talked about how late in his career he has rediscovered his love for Jiu-Jitsu and rolls a lot more often. He recently outwrestled and submitted RDA at Submission Underground and a few days ago he had a Combat Jiu-Jitsu match with Craig Jones (he lost, of course, but that's to be expected against Craig Jones). He's also been doing some BJJ instruction for fighters.
I know Paddy is a primary grappler and very skilled in that arena himself, but he's been outgrappled in his career (admittedly by fairly skilled fighters in Soren Bak and Nad Narimani). He's also the smaller man (ex-Featherweight versus occasional Welterweight).
In other words I think it has less to do with where Paddy is stronger and more to do with where Cowboy is less weak in his current state. Cerrone hasn't been convincingly manhandled by someone Paddy's size and experience level in a long, long time. Conversely he has a long history of outgrappling/submitting dudes (including some with legit grappling pedigrees), oftentimes off his back.
