We're about to look at this two different ways, so stay with me and read carefully.
Primer: Cap Space vs. Free Agency
It's really easy to rank teams by their cap space this offseason and say that the ones with the most space will spend the most money. However, with the way that NFL contracts work, most of the money that is signed for in free agency this offseason won't really hit the books in a significant way until next season.
Let's imagine an imaginary player signs with the San Diego Chargers on a 5-year contract worth $50 million. The first thing to look at is the signing bonus. Let's imagine that signing bonus is $15 million, and that's cash that gets handed over to the player as soon as he signs.
That $15 million gets spread across the life of the contract (usually), which means it goes against the cap in increments of $3 million per year.
Now, because the team just handed the player $15 million, he's not short on cash. So they can play with their cap space by paying him a minimal salary ($500k in our imaginary situation) in Year 1 of the deal. This is harder to do in Year 2 or Year 3 because the player hasn't just been handed a big check and it offers him less security, as a low salary could make the player easier for the team to release down the line (this was the out that the team had built into Donald Butler's contract).
In our imaginary scenario, the player's Year 1 "cap hit" would be $3.5M. It wouldn't be until Year 2 that the cap hit would jump up into the $8M range.
With that in mind....
San Diego Chargers' 2016 Cap Space
The Chargers' current Top 51 spending is currently at about $120 million.
The salary cap for this season is set at $155 million, and the Chargers have another $2 million carryover that they didn't spend last year.
That leaves the Chargers with roughly $37.5M in cap space in 2016, which currently ranks as the 12th most in the NFL.
To put it another way, the Chargers have an average amount of space space this offseason that is dedicated to the upcoming season (and that's before the assumed Antonio Gates signing). That's a tough pill to swallow for a team that just went 4-12, but that's what happens when to pay guys like Philip Rivers and Corey Liuget to be your superstars.
San Diego Chargers' 2017 Cap Space
Here's where things get interesting...
As I stated above, most free agent contracts don't really affect a team's salary cap all that much in Year 1. Where they start to affect things is in Year 2. Unfortunately, we have more to add to our math equation.
Almost every team's 2016 cap space is reflective of the team having 51+ players signed to the roster for the upcoming season. When it comes to the 2017 cap space, things get a little murkier.
The Chargers jump from 12th in cap space to 4th in cap space when you move ahead to next offseason, but they also only have 23 players signed past the 2016 season. So, while that may seem like the team will have loads of cap space next offseason, they really won't. The only way the Chargers could protect all of that cap space would be if they filled 20+ roster sports with rookies.
Tom Telesco will have to be careful this offseason, because he'll have to keep an eye on his 2017 cap space and make sure he leaves enough to actually pay for the team around whatever superstars he wants to sign this offseason. I think that will keep him from making any major splashes in free agency this week (sorry, Malik Jackson), and keep him shopping in the bargain bin.