Pete Carroll and John Schneider have to be kicking themselves over how badly they screwed up with Mark Glowinski, who has to be just as happy that they released him from Tom Cable’s broken system in 2017 so he could get his career going in the right direction.

The guard was a good pick by Seattle in the fourth round in 2015, coming off an excellent college career at West Virginia, and he should have become one of Seattle’s line mainstays. Instead, Carroll and Schneider let him go in 2017 and he turned into one of the Indianapolis Colts’ best linemen in 2018, earning a contract worth $6 million a year.

Glowinski is the latest — maybe the greatest — example of how Cable’s system held players back in Seattle.

Glowinski started all 16 games at left guard in his second season — on a line made up of five guys with just five combined seasons of NFL experience. In 2017, he was benched for Oday Aboushi and rookie Ethan Pocic, starting just two of the 10 games he played before the Seahawks stunningly waived him in December.

So Glowinski went to Indy, where he re-emerged as a starter in 2018 after longtime vet Matt Slauson was injured, and became one of their core linemen.

The Seahawks, meanwhile, were a step late in replacing Cable with Mike Solari, who quickly straightened out Germain Ifedi and coached the league’s top rushing line — even though he used six line combinations (the Hawks have never used fewer than five under Carroll).

With Glowinski gone and Pocic not good enough, the Hawks are still looking for guards. They used veteran stopgaps last year and are hoping to re-sign J.R. Sweezy and/or D.J. Fluker — for maybe a third of what the Colts paid Glowinski.

Pocic, a second-rounder in 2017, has been a major disappointment so far. But maybe 2019 is the year he steps up. The Hawks also have Jordan Simmons, a nice waiver addition last year who helped plow the way for two 200-yard rushing games.

The Hawks need to plan a future for this unit — ideally through 2021. Right now, Duane Brown and Jamarco Jones are the only guys signed that long. Justin Britt and Pocic are signed through 2020, when Simmons will be an RFA — and the rest are all up in the air this year or next.

In an ideal world, Seattle would re-sign at least one of the guards for three years and then let 2019 decide their 2020-21 right tackle — Ifedi, George Fant or maybe Jones. They also could draft a lineman, with the hope he fills in one of those OG/RT spots in 2020-21.

But, knowing Carroll and Schneider, they will just play it one year at a time — keeping their line forever in chaotic flux.