What league are you in (or more specifically, your opponents)? Bronze has a lot of variability, as some of them are new drafters, and some might have just skipped a set and dropped down to bronze again. It's also near the end of a draft format, so there may be fewer people playing, causing a greater mismatch in your and your opponent's ranks.
If both you and your opponents are in silver+ leagues, I'd be surprised, but this isn't unusual for bronze.