Yanagi is part of the Big 3 so at least people consider him to be on the same tier as Sanada and Yukimura, even though it's hard to see why he'd be in that tier. Nobody would consider Tachibana the same tier as Sanada and Yukimura. I think Yanagi is way underrated in the series because of his relationship with Inui, but he's supposed to be only slightly weaker than Sanada. People talk about the big 3, not "Sanada Yukimura and his sidekick".
If you go back to the original dialogue about Furinkazan, Yanagi said once he had Sanada on the ropes but then he can't do anything once Sanada used Rin. However, unlike the other cases of that flashback, we know Rin is definitely not data tennis. That is, we know Sanada can beat Kirihara with ka (power vs power) or Atobe with zan (endurance vs endurance), but Rin versus Yanagi is definitely not data tennis versus data tennis. I realize at that point Konomi might not have even thought of what Rin is supposed to do, but since Sanada has nothing in common with data tennis this implies this is a victory that wasn't a 'head-on' victory, and the only other person that Sanada needed to do that was Tezuka.