Just gotta keep them still. 2b 5b is pretty good for that. If they dont barrier either they get comboed, even if they do, they go back to the ground. 2b 5b is mostly to get people to not jump out after your crouching midscreen bnb. (5a 5b 2b 5d tk623b)
For normal blockstrings use 5b 6a or if you have them figured out use tk623c. Also 5a 2a staggers