This was an impressive debut for Watson, even if we recognize neither fighter has a Wikipedia entry at this point. That sounds like a flippant remark, but it just underscores how new in their careers both fighters are.
Not much to assess about this one. A superior muay Thai fighter in Watson was able to fire off a well-rehearsed jab-right high kick combo to devastating effect. There's an open question about the stoppage under the hands of Mario Yamasaki, however. Sandoval was clearly hurt, but appeared to be actively reach for a single leg takedown when Yamasaki stopped the action. And it wasn't the sort of stoppage
Here's how our Nate Wilcox covered the action:
Round 1 Sandoval takes center cage. Watson circles away and fires with kicks. A low kick to Sandoval's groin forces a stoppage. They restart. Watson catches Sandoval coming in with a high kick to the head. Sandoval, stunned, backs away and Watson lands a 1-2, then drops Sandoval. Watson followed him down, teeing off on Sandoval. Referee Mario Yamasaki stops the beating at 1:17 of the first round.
After the bout, Watson thanks Sandoval for the opportunity and is congratulated for his UFC debut win.
Watson was impressive, taking quick advantage of a significant height and reach advantage over Sandoval. The brief showing however leaves a lot of questions about Watson's game