Just guessing, those few degrees won't make any difference, the slight tilt isn't for the purpose to intercept the top attacking missile. Due to the very high speed of the missile, the detection, calculation of timing of launching and sending commands to the interceptor projectiles should have been done well before the incoming missile reached the blind spot of the radar. It would be toooooo late if you still need the radar to see the missile above your turret. You should have destroyed the missile well before it enters 10 (just a figure) meter radius, after that everything is too late.It look like israel iron fist aps system,but most the aps radar tilted few degree upward,so it can intercepted top attack missile flying at much higher angle such as javelin atgm.and most of the forward radar were located near the frontal turrent so it can intercept HEAT/kinetic round and missile head on.