Yes the two of them together are weaker, their performance against BM is worse than Luffy's performance against Kaido, Kaido is the centre of attention this arc.
Kidd/Law are saying here they just want to stop her from getting to the roof, while Luffy is 100% personally assured of his victory.
Kaido "lost" the mini fight last chapter, and has "lost" most mini scuffles with Luffy looking slightly more dominant than him since starting this final 1vs1, yes Kaido has trump cards left on the table, so does Luffy.