With recent OL issues how patient will Hawks be before contemplating a trade for help? Is there anyone worth trading for?#HawksMail

— Chris Amico (@amicochris) September 19, 2017

This has been a popular question -- in one form or another -- in light of the here-we-go-again start for the Seattle Seahawks' offensive line. Really, it's been a popular question for a few years.

As general manager John Schneider will often mention, Seattle's front office prides itself on at least kicking the tires on any move that could improve the team, so it's a safe bet that the Seahawks have looked into potential trades to help them out up front.

But it's not that simple. Availability and cost are issues.

Start with the reality that the NFL has what sure seems to be a shortage of quality offensive linemen, with the general belief being that the proliferation of spread systems in college football is mostly to blame. Offensive linemen in those systems typically aren't asked to play from a three-point stance or fire off the ball, which can leave them ill-prepared for the way the game is played in the NFL.

There really aren't that many to go around in the first place, which means there are even fewer who would be available in a trade. So the Seahawks or any other team trying to upgrade its offensive line this time of the year is going to find it difficult.

That's not to say that trading for an offensive lineman is a non-starter. Seattle has done it twice in the past five weeks, acquiring tackles Matt Tobin from the Philadelphia Eagles and Isaiah Battle from the Kansas City Chiefs. But they're both backups. While they have the potential to become more down the road, they're not the types of players who are going to significantly change the fortunes of an offensive line right away.

With the few who may be available to Seattle and who would constitute a significant upgrade over what the team currently has, the price to acquire them could be prohibitive in terms of draft-pick compensation and/or salary.

Consider their recent trades. The Seahawks gave up a fifth-round pick for Tobin (and also got a seventh). They gave up a seventh for Battle. If that's what it cost to acquire two backups, then the going rate for an above-average starter is going to be a whole lot steeper. And remember, Seattle no longer has its 2018 second-round pick after parting with it in order to acquire Sheldon Richardson. That will impact the Seahawks' ability and probably their willingness to pull off a significant trade for an offensive lineman.

Even if the Seahawks had their full complement of draft picks, money would be another issue. The Seahawks already cut starting defensive tackle Ahtyba Rubin and restructured wide receiver Doug Baldwin's contract in order to make room for Richardson's $8.1 million salary, two things the team would have preferred to not have to do.

Cleveland Browns left tackle Joe Thomas is making $8.8 million this season. Left tackle Duane Brown, who is holding out from the Houston Texas, is making $9.4 million. And if he's not willing to play for his own team for that amount, any team that would trade for him would likely have to give him a raise. The Seahawks aren't in a position to take on those types of salaries.

The lesson in all of this is that the time to acquire key pieces to an offensive line is March and April. The Seahawks did that, to some extent, by signing Luke Joeckel and Oday Aboushi in free agency before drafting Ethan Pocic in the second round.

It's much harder to do come September, especially if you're like the Seahawks and you don't have an abundance of draft picks and salary-cap space.