Worstgen
Gol D. Roger
One of the key reasons why @Bogard thinks Marco is a top tier is because Marco, along with BB, was considered a contender for WB's replacement.
Shiroyru
Yes but he also uses Marco’s performance against the Admirals as a key reason. We know that Teach dominated Marco in their fight, so that would put Teach above the Admirals
Gol D. Roger
To be frank, the manga doesn't say anything specific about BB and Marco. But BB is certified top tier while Marco barely hits that level(acc to @Bogard) so it's only natural the new Yonko dominates.
Shiroyru
Robin said that the WBP suffered a crushing defeat. Marco had the backing of the entire WBP and allies while Teach only had his main crew members + whatever allies he gained in a year. Very unlikely that Teach gathered a larger following in one year (before he even got his Yonko title to attract people looking for protection) than WB gathered in his entire pirate career.
Shiroyru
So it would make no sense for the BBP minus BB to crush the WBP minus Marco. The crushing defeat was the result of Teach being much stronger than anyone else there