Apart from Marco and Jozu none of the Whitebeard commanders are particularly impressive imo. It took most of the 16 to barely stop Akainu. Only Marco and Jozu really gave the Admirals any trouble like at all.
Plus Big mom crew runs way deeper
We still haven't seen the full power of Smoothie yet. Snack was defeated by one of the post time skip Worst Generation so he's not a pushover.
Perospero is really strong. He's able to turn entire portions of the sea into candy, turn people into candy, and was able to stop Bege's giant castle form
Oven can make anything melt with his df. Daifuku was giving Sanji that work with no effort. I'm not a Sanji fan but he's no pushover either.
Vista? He briefly clashed with Mihawk and it's implied that he's one of the top three strongest on the crew. We didn't see what happened after that panel, plus we have to understand that marineford was riddled with inconsistencies.
That's only because WB lost 3 of his top members. Both Ace and Thatch were killed and Blackbeard defected. If they stayed as a crew it wouldn't have been close in terms of power compared to the other Yonkou crews. You could argue that Snack is a pushover if he lost to Urogue because we've seen how Luffy struggled against Cracker and he was barely able to beat him. Mind you, this is a post time skip Luffy who trained with Rayleigh and who we can safely assume is a top 2 supernova.
The thing is we haven't seen much of anything from WB's crew, and from what we have seen it was against top tiers. I can't envision the Strawhat crew running up on WB's territory and doing what they've done to BM with no repercussions. I'll admit some things have been convenient for the Strawhat crew, but still, by the end of the arc, we are going to have 2 of the 3 commanders down and possibly even 3 if Smoothie decides to do something.
I'm of the belief that all of the Yonkou commanders are on the same strength. So, all of the first hands will be roughly equal with little differences and same goes for the 2nd, 3rd, and 4th.
Well we have queen smoothie who has the ability to squeeze out out life juice from her opponents, and grow to the size of a giant and uses elbaf sword techniques. Also , you have Lord oven who even with a devil fruit power can heat the oceans with near boiling temperature. Praline has the ability to call sea creatures and sea beasts. Pudding is manipulative and can alter memories, Charlotte snack who is almost at the lost generation level. Then Charlotte brulee is also pretty dangerous as she can in an out of mirrors and change into different characters. All these guys are pretty strong tbh. Of course a whitebeard crew could handle them. But Straw hat pirates are on the exceptions that managed to evade getting their shyt split by the Charlotte pirates, and if you go back you would realize that a lot of it is due to sheer luck
We haven't seen Smoothie do shyt to anyone besides Reiju. Brulee is not strong and neither is pudding. They would probably pass out if they got hit by Kat/Luffy's Conquerors haki. I agree that it was due to luck and plot convenience.