Manning over Tebow. Ok, that's an easy choice in the short term. Surprisingly from Tebow's wins-losses, but not surprisingly from coaching practices, little interest in a trade for Tebow existed around the NFL. By reports, only the Jaguars (owner, not coaches) and Jets (coaches) showed interest. For teams with QBs by the names of Rogers, Brady, Brees, E. Manning or even Rivers, Romo, and a few others, the disinterest makes sense. For teams with serious QB issues, the lack of interest only makes sense when considered as part of the risk aversion of coaches.
Coaches are notorious imitators. If Joe Montana or Troy Aikman rack up championships based on using a high pass completion percentage "West Coast" scheme, well, then everyone needs one of those. The problem -- few QBs match the specific skills of Montana, Aikman, Brady, Manning, or Brees. Even with QBs that clearly don't match their skill set, coaches will try to cram the square peg in the round hole with only adjustment around the edges.
Why so little wholesale offensive innovation, so little willingness to customize offensive schemes even when the resources available are different? Incentives are the first place an economist looks. In the simplest of economic worlds, managers are risk neutral. Owners take the risks. In more realistic, expanded settings and models, managers bear risks based on the specifics of contractual relationships within firms.
No doubt, coaches are incentivized to win games. Consistent winning keeps a coach employed. Winning big sparks higher salaries and new job opportunities. So, take risks, win games ... Maybe not. Taking large risks, walking out on a limb by bucking trends, if unsuccessful, can lead to excessive fan and media criticism and to quick firings and diminish future job opportunities relative to mediocre results. These combinations of incentives produce incremental adjustments to existing methods but few real innovators. Departures occur only when owners or a desperate situation leave little other option. We see much more radical innovation in college football because the talent disparity generates more desperate circumstances. For example, Northwestern gambled on the modified single-wing, spread-option attack in the 1990s. Purdue under Joe Tiller employed a slightly different version. Now, the spread has swept college football.
Radical innovators are often seen as "mad scientists." Sid Gilman played this role with Don Coryell and Bill Walsh winning many more games and receiving much wider recognition for refining and improving on Gilman's ideas in ways that then became widely adopted by the league over time. The "mad scientist" label even stuck to Coryell to a certain extent.