1) Only Piccolo and Vegeta said to have been training like crazy
2) Vegeta immediately compliments Piccolo as a warrior for suppressing early
3) Piccolo and Vegeta possibly beating Freeza.
4) Piccolo's willingness to fight Vegeta
5) Piccolo's dominance shown throughout the telling of the Androids story
Piccolo is portrayed as a a badass mofo in the Trunks Saga. All subjective, all opinion, but god damn I'm a give him some credit actually and picture this the only time Vegeta vs Piccolo would have been a badass fight of epic proportions.
In general in most arcs, the supporting characters close the gaps from the previous sagas massive gaps.