First round of this video by Akira gives a better example of how Tager's 5B can be used in footsies vs Ragna:
http://www.youtube.com/watch?v=jkW3ntkxFHA
@ 16 seconds, Tager's 5B stuffs a dash in 5B from Ragna. You can buffer a A-Sledge during your 5B, like Akira does, and it won't come out on whiff, but it'll come out if you hit the opponent.
First round also shows Akira IB 360B-ing Ragna's 2B as well, so you can see that in action as well.
Rather not show that vid of me since I'm literally just spamming 5B and I only land it like twice.
Speaking from experience though, this only works if the Ragna likes to dash in before an attack. If the Ragna player just spaces himself by standing at max range and pressing buttons, it's basically impossible to react to. If you're going to use 5B in footsies, you're basically reacting to the dash rather than the poke itself, because the idea is to have your 5B out before Ragna's attack.