There is a narrative that free agents should be avoided because the bang they bring is too often outweighed by the cost.  As many like to note, often there is a reason why these players reach free agency.  Is there a tendency to read about the high-profile players who were busts for their new teams rather than those who played well?  Does the national media ignore the lower profile types regardless of whether they were good or bad?  

I looked at a PFF article that provided an instant grade for all the free agency deals that were made within about the first 24 hours of the beginning of free agency in 2017.  That would be during what some describe as the free agent frenzy period.  I decided to grade the actual results of those signings two seasons later.  It is possible that my grades would be different for signings made four or five days after the frenzy subsides, or after the draft. 

I have listed the results below.  The first table shows the eleven signing rated an "A" by PFF with my grade for each player-signing based on performance and modified by the cost. 

These eleven signings grade out to a C or a bit better in my opinion.  There were 31 signings given an instant grade of B.  Here is a truncated table showing these deals:

I gave an aggregate grade of C-  to these 31 deals above.  There were 17 deals instantly graded as a C by PFF in the table below:  

Overall, I gave these 17 deals above a C.  There were 16 players with an instant grade of D noted in the table below:

I gave this group of players above a collective C- grade. Finally, there were four free agent signings instantly graded as an F which I have noted below:

I gave these deals a solid C grade.  The average grade for all 79 players was mid-way between a C- and a C.  The median score was a C- grade.  Regardless of whether the instant grade was an F or an A, my grade for each group based on my view of their actual play ranged from a C- to almost a C+.  

The eleven contracts with AAV over $9.5M (chosen because that's the number that earned a third-round compensatory pick) received exactly a C average. My grade remains a solid C even if I drop down to all contracts over $8.5 million.

29 teams participated in free agency, with 13 signing more than two free agents.  Seven teams selected more than 3 players, five more than four players, and two teams selected more than five players.

The Bears selected seven players whose average grade was a D.  That included four players with some kind of an F grade, one D+, one B+, and one A- grade.  San Francisco received a D+ grade for its five signings. Jacksonville received a C+ for its 5 signing and Carolina got a B- for its five signings. The Patriots signed just two free agents and received a grade midway between a B and a B+. 

As a note, I tried to make actual performance the most important consideration, with cost just a modifier usually worth a plus or a minus rather than a full grade letter.  Calais Campbell and Mike Adams are good examples. 

Calais Campbell has been a dominant player since his signing: his play has been worth an "A" so even though he got paid very well, I did not modify his grade.  At most, I did not add a plus to his grade due to his large contract.  The old safety, Mike Adams, started for his team and played at a well above average level.  His play was probably a solid "B" but his $1 million cost makes him an "A+" in my view.  Lance Kendricks' play might have been worthy of a D+ (he was rated as average, the #44 TE with a 60.5 grade by PFF), but his modest salary and structure bumped him up a bit to a C-.  I am sure I am biased by the cost.  I tried only to modify a grade by a full letter or two if the contract was grossly out of line with the player's performance, either up or down.  Jimmy Graham's performance in 2018 is probably worth a C- but due to being the highest paid tight end, I feel his grade should be modified down by a full letter to a D- or even an F+. 

I may have subconsciously modified grades if they appeared to be one of the missing pieces that a team needed to succeed; I know that thought flashed through my mind a few times.  LT Okung might be an example.  The Chargers may have overpaid somewhat but teams need a good left tackle to get deep in the playoffs.

Conclusions:

I did reach some tentative conclusions.  Teams can increase the talent level on their teams by using free agency.  Teams can also simply waste cap space.  Jacksonville and Carolina had good seasons after each acquired five free agents without bungling too many of them. 

There is a premium paid but it appears to be within reason, more like the agio one pays when exchanging dollars for euros or buying and selling gold. 

The instant grades by analysts do not appear to correlate with actual results. 

Giving out big contracts to free agents got roughly the same grade as medium and small ones, though the colossal blunder risk increases.  The Nolan Carroll signing got an F- from me but that resulted in only $4 million being wasted: a player with a giant contract who utterly fails will also get an F- but might have a larger effect on a team.

I also looked at trades and the draft while researching this article.  I am going to save those for later to see if there is enough there for an article.  I could not help noticing that some teams (and Belichick caught my eye initially) seem to do a better job of evaluating players already in the NFL than in drafting college prospects and projecting how their skills will translate to the NFL and specifically to their respective teams. 

I believe the Packers will have $23-$30 million in cap space available to spend after signing the draft.  Should they spend it on a few players with big contracts, several players with small to modest salary requirements, or should the team save most of it, merely re-signing a selection of the team's own free agents?