in MTT's (Multi Table Tourneys) at the beginning it pays to play tight and win a small amount of big hands, The problem i think you are having is that when in the later stages someone has a big chip lead they can start to make it hard for players on smaller chips to play hands, as a chip leader in a big tourney you can steal the huge blinds by playing aggressively, making the smaller stacked players play tighter. When in this situation you need to defend your blinds, you need to try and combat the aggressor, when he makes a raise in an early position you need to re-raise him all-in you need to take a few risks on medium ranking hands, especially in free-roll style multi tournaments, everyone is going for the win and will take many more risks.
Additionally you rarely ever see a truely tight player win a tournament. When you have the chip advantage you want to be making raises pre-flop of about 3 times the big blind, forcing the smaller stacks to fold. Dont play in MTT's for the money, play for the win, 2nd is to me as bad as coming last. Get your chips out there, and play high Suited connectors( 7,8 upward) , Pocket Pairs, and premium hands, dont wait to long to get your chips in there if someone is dominating the play. | 
