The skill level of people I play with in team builder and the ones in blind pick are drastically different. I'm talking like, 2 complete divisions. Are the MMRs different, or is it just a coincidence?
Yes, it has a different MMR. Teambuilder's MMR is also based on your champion.
https://www.youtube.com/watch?v=Z4P7yakJyg4 <- Sorry for the truth sir
My understanding is they use the same base MMR, but it's adjusted based on your performance with specific roles and champions in TB games.
Third-party sites that try to estimate MMR can be wildly wrong, especially for Normal matches. They're almost always showing you the player's estimated ranked MMR, which 1) might not be very accurate even in Ranked and 2) is going to be even less accurate for how they play in Normals.
