#4 A "real" fighter
Despite having trained with former UFC Lightweight Champion Anthony Pettis, current UFC Welterweight Champion Tyron Woodley as well as Ben Askren (a highly accomplished amateur wrestler who is currently undefeated and previously held the Welterweight title in both ONE FC and Bellator) -- all under the tutelage of widely respected former kickboxer and world-class coach Duke Roufus at Roufusport -- CM Punk failed to win even a single MMA fight.
Although Mickey Gall may have been too tough a challenge for Punk, the man known as Mike Jackson whom Punk lost to decisively at UFC 225, is regarded by many as a regional-level MMA fighter. Regardless of which, Jackson managed to control, mock and dominate Punk in the Octagon; besides also quite literally slapping him around with ease over the course of 3 rounds. On an edition of the Joe Rogan Experience (JRE Podcast), veteran UFC commentator Joe Rogan strongly asserted that Punk has "no athletic talent".
On the contrary, Kevin Nash was the go-to guy in a confrontation or a melee scenario all through his time in WCW and WWE in the 1990s and early 2000s. Now, granted that knocking a drunk bar patron out is considered to be easier than winning a professional MMA fight, however, a bar fight or street fight scenario is undoubtedly riskier -- not only because of the potential of being attacked by multiple assailants but also due to weapons (guns, knives, etc) being used.
Be it in his altercation with Don DeVoe, his fights on the college campus, or in the altercations on the road where he protected his fellow wrestlers; Nash is someone whom none of the troublemakers messed with. Add to that his training and experience in the armed forces, and you have a "real fighter" who just so happens to be much more dangerous than a man about 20 years his junior...