Hayden was so close to making one of the most brilliant moves of Survivor history! His idea to vote Monica was amazing! He knew at best it would come down to a rock draw. So by voting Monica it ensured that Tyson would be vulnerable for the draw. Brilliant! However, that wasn't the plan he should have used. Since Tyson is keeping the idol under wraps, Hayden could have pretended to find the idol. This would cause the alliance of Tyson, Gervase, Monica, and Ciera to split the votes. 2 for Katie, 2 for Hayden (Monica or Tyson would get Katie and Hayden's votes): thinking Hayden or Katie would play the idol and the other would go home. So Tyson, Gervase, and Monica think the vote will come in 2-2-2 and on the revote they vote out whoever didn't play the idol. BUT, Hayden flips Ciera because she knows she is fourth. Instead of following the split votes plan, Ciera votes for Tyson or Monica (whoever they decide) and the vote comes in 3 (Monica or Tyson)-2 (Hayden)-1 (Katie). Monica/Tyson is blindsided and the newbies have the numbers.
I know it is a bit of a stretch, but if Tyson is that desperate to keep the idol a secret, he wouldn't object to splitting the votes. Also, if Tyson does reveal he has the idol to prevent splitting votes. Hayden could fall back on the plan he used tonight.
So in conclusion, Hayden made a great effort. However, he could have succeeded with a little more thought!