I have a feeling the fight against Sankou is getting set up to be more of a hitting match. Both schools have insanely good batters, but pitchers that are, for now, merely A-tier instead of S-tier.
In contrast, the battle against Inajitsu will involve Sawamura needing to be far more refined in his pitching, since Narumiya is guaranteed to keep the score low even against Seidou's lineup. I'm thinking 3 runs max, at least through the 9th inning.
If this manga does extend into Sawamura's 3rd year, then with Mei gone he shouldn't have any competition in Japan besides Masamune (and maybe Furuya). His trajectory so far is way too strong.