Yeah I would say low 130 too. But Bird's got quite a lot of his wickets through bowled/lbw so to hear that batsmen are being surprised by his speed isn't a shock.
It really depends on how they're getting them. So yeah a bit of both. With Butterworth and Faulkner it's hard to get too up in arm, because those two are damn good at extracting any bit of life they can from the ball/pitch. But with Cutting and Herrick whenever I see them bowl I just don't see anything too special apart from their higher than average pace and they're putting up some pretty amazing stats.
Much of Herrick's success comes from bowling stump to stump. No margin for error for the batsman if done for speed. Unfortunately it is this modus operandi which makes him very hittable in the shorter versions of the game.