sometimes when my friends cyrax uses 2,1,2, after the 2,1 i can somtimes d1 him but only like 1 every 10 times. Any thoughts? is it my inputs or the game?
21 does not jail into 212. You're at enough neutral frames in between the string to poke him out. Other examples are raiden's 334, sz's 212, noob's 212 etc. It's risky poking him out, most people use armor to interrupt strings, which is also recommended for strings that leave you neutral in between but not enough frames to poke out.
This is why I stopped using the 212.
Better to cancel into something else after the 1. Jump over with an AA Throw, Ragdoll, Saw...builds meter & prevents pokes.