The key issue in the Solution Battlefield is to be honest in your own evaluation of the fit between the customer requirements and your solution. It is part of the make up of most sales guys that they sincerely believe in what they are selling and have convinced themselves it is the right solution for the customer.
This is a very powerful subconscious message and I would encourage you to maintain this attitude. However, if you cannot look at the competitive scenario and say honestly whether your solution or the competitors has a better fit with the known requirements, then you will suffer some surprise losses. What is even worse is that you may have been able to win, if you had understood that you were losing this battlefield and done something about it.
You do not have to win every evaluation 5-0; 3-2 is still a win and in selling winner takes all.