This is a bit irrelevant, as you must use T/T or K method, so not much possibilities of big lead in epsilon....
As per more than 4 degrees lead - it could be due to unguided flight of missile (until hitting the strobs on >2.1 km range...
In Epsilon in case of H<5, the boresight is moved down electrically by 3 degrees. If I consider +-4 degree of elevation lead from the mechanical boresight, than in H<5 the lead can be -1 .. +7 degrees from the electrical boresight.
Please, check the page 356 (end)-360 of the "Supplementation to the Rules of Shooting fir S-75M" (from where you show me the killing zone for receding target) and tell me how you understand it...