When milk is poured on the Shiv Lingam to do Abhishekam (Milk Bath) the flow of positive energy starts getting accumulated towards Shiv Lingam.
So a person who is devotee of Baba When he is closer to the Shiv Lingam & Bathes Shiv Lingam with milk He gets to receive the flow of Positive energy into his body.
The milk bath of Mahadev bears Special significance for the devotees.