This post brings up some unique, fairly hidden truths about special teams play but reaches the same conclusion all have reached nevertheless: slapping the franchise tag on Shayne Graham, in effect making him one of the most highly-paid kickers in the NFL, was an idiotic move, parallel with many others made by he-who-shall-not-be-named. Fortunately a long-term contract has not been given to Graham (contrary to the opinions on here and here), but there is still this move to discuss.
To begin with, the obvious- spending a great deal of money on a kicker does not make a whole lot of sense. Special teams as a whole is worth relatively little when compared to offense and defense, and using the money on a player who may not even be an asset in (I'll explain) the less-important unit, rather than one who will increase the strength of the important one like a third cornerback, is ridiculous.
Football Outsiders is one of the best NFL sites online, creating new, better statistics to help us further increase our knowledge of the NFL, as well as giving us somewhat radical discoveries. One of the more interesting ones was described in this New York Times article in November of 2006. Basically, their findings told us that we had been judging kickers the wrong way; field-goal percentage, the most common stat used to assess a kicker's performance, had little year-to-year correlation (for all of the details, refer to the article). The statistic most consistent year-to-year, and therefore the only dependable one to judge a kicker on, was kickoff length.