The onus is on Topalov to force the issue and unbalance the positions to get himself winning positions now that he has fallen behind. Extended series of draws are not new in Championship matches; even Fischer-Spassky had 8 consecutive draws. And Kramnik was down one against Leko with 6 games to go in their match and there were 5 draws in a row, but the guy who supposedly only plays for draws was able to win the last game and retain his title.