It depends on your defense. If you play a lot of 3-2 zone, you almost don't need SB on your guards. But if you play m2m, especially against LI, SB is a gift for your guard. It's not as powerful as SB on the bigs, but it's still enough.
Haek had his best SB season as a guard during Season 27. He had 2.2 blks/game as a PG (11 games - 3-2 zone). Compaired to his best C seasons (S-26 5 blks/game and S-28 4.7 blks/game - also 3-2 zone, 12 games each season) it's low.