I guess most MT basic designs (those given in IE) are flawed at one degree or another because they mimicked those given in CT, adapting rules to that, instead of designing them with MT rules and accepting the changes needed.
About gunners, I've adopted the HG rules of needing one gunner per battery (one per turret if using mixted weaponry), 2 per bay and one per 13500 kl of main weapon/screen.
See that using pure MT rules, to mann a 1 rated Black Globe, you need 50 crewmemebers (15*400/0.1/10/120).
Black Globes are very high-TL though - things may be different there.