Everyone worries about a bad contract down the road, but a huge hole on the field hurts a lot more. There is risk either way.
Personally, I think its a little more complicated than that.
A bad contract results in a "hole" on the field as well plus you get stuck with that player because he's too expensive to cut (loss of flexibility), cap dollars are lost, it stops the progress of other players and all the risk is placed on one player who having just received a fat contract may not have the same hunger he had when he was striving for that big contract.
Additionally the player a team has to utilize in lieu of the high priced free agent won't be completely worthless (if you're in the NFL, you have some level of talent).
For example, lets say the high price free agent gets assigned a value of 100 on a scale of 0-100 and has reached his ceiling performance-wise and the team hopes it will continue for the duration of his contract. Whereas the player you'd have to settle on if you don't acquire the free agent scores a 70 on the scale but has a contract that can be gotten away from easily, has the potential to improve and frees up additional cap dollars to devote among other players which effectively diversifies the risk and might allow you to improve other areas of the team.
So in my example, the question becomes do you invest in one player to potentially achieve 30 percentage points higher production than the alternative player in exchange for not being able to address other areas with cap dollars saved by not signing the high priced free agent, lose flexibility due to contractual obligations, hinder progress of other players and put all the risk on one high priced free agent.
Perhaps you should, perhaps you shouldn't, these are decisions for the experts but I totally agree, there is risk in either scenario because there are no guarantees in life and especially in the NFL.
The current system, more than any other time in the NFL imo, shows how important it is to build a team that gets contributions from as many players as possible and it seems to me when too many cap dollars are devoted to too few players, success never ensues.
IMHO, it comes down to managements ability to identify, acquire and develop talent and then to creatively and efficiently assign cap dollars to those players. It appears the current staff might be on a roll at doing these very things and success going forward will depend upon this continuing, not making the biggest splashes in free agency.