Piechota was completely dominant for his first 2.5 UFC fights before gassing out in round 3 vs Meerschaert. And Meerschaert isn't a bad gatekeeper, beat Giles, deserved the win vs Holland. He has only been dominated by rising contenders Santos + Hermansson.
Piechota is well rounded, can finish on the ground or standing up. Seems like a pretty good prospect if he just learns to manage his cardio better, and he has had over a year off to regroup and improve since the GM3 fight.
Vieira OTOH is super green, has been training MMA for only 3 years. Looks like he cannot strike at all, and while his wrestling is improving it's still massively unproven vs any real opponent. Nemchinov was 10-0 but fought suspect competition, and now Piechota is a huge step up in competition.
I can't fathom laying juice on Vieira. It's questionable whether he can take Piechota down and hold him down. Against Jacob Holyman-Tague he needed like 5 takedowns bc the guy kept getting up, and he had recently been subbed by this scrub so his grappling D is almost certainly bad:
https://www.tapology.com/fightcenter/fighters/48380-darcy-vendy
And every minute standing up may be painful for Vieira. Piechota is going to be the better striker, likely by a huge margin, and he should be a huge KO threat. If there is any turbulence whatsoever getting this to the ground, Vieira bettors are going to have sweaty palms.
I personally believe Piechota is the better prospect who is more developed as a complete MMA fighter, and should be the correct fave this fight. Everybody laying juice on Vieira is getting drunk on extremely expensive hype. He is massively unproven, and BJJ isn't a good base if it doesn't come with striking and wrestling.
Sure Piechota may gas again, or maybe this time he doesn't or maybe he gets a 1 minute KO and it doesn't matter. Regardless I don't see any clear reason to favor Vieira outside of hype, this is my fave bet this week.