Hub Arkush: Bears' O-line is now their Achilles' heel

The recent rapid-fire signings of Deon Bush, Artie Burns, Jordan Lucas and Markevious Mingo suggest the Bears are all but done with any big swings in free agency.

Bush will be the presumptive starter next to Eddie Jackson at safety, and even though Mingo and Burns are former first-round picks, what all four of these players have in common is that their main contributions to NFL teams to date have been on special teams.

Ryan Pace's focus this week has clearly been on the bottom half of his roster.

But when you consider as the starter's bell rang a week ago Monday that the Bears' most glaring needs were at tight end, quarterback, safety and pass rush, whether you like his approach or not, you can't argue that Pace hasn't addressed every one of them.

The Bears should be able to address additional concerns via other avenues, including two second-round draft picks and five more in the fifth, sixth and seventh rounds. There are also trades available - witness Pace's quarterback strategy.

However, I chose the phrase "glaring needs" two paragraphs back strategically.

Since the Bears will return all five starting offensive linemen from last season, it's hard to call that unit a glaring need.

Unless, like me, you believe the left tackle isn't NFL-starter caliber, Rashaad Coward and Alex Bars are still complete unknowns, and left guard James Daniels and center Cody Whitehair both finished the season out of position and head coach Matt Nagy is dropping hints he may leave them there.

Throw in swing tackle Cornelius Lucas, the most valuable backup on either side of the ball and the versatile Ted Larsen inside are both gone, and you've got a big problem.

Let's be fair: I've pointed out several times the last few months this was a bad year to seek free-agent help on the O-line.

Contracts given to guys like Halapoulivaati Vaitai, Ereck Flowers, George Fant and Alex Lewis - literally just "guys" - have been somewhat absurd, and the Bears didn't have the cap freedom to mix it up with Jack Conklin, Anthony Castonzo or Bryan Bulaga.

As much as I think Jason Peters would be a great idea, he is 38. The Bears could still go to market for Trent Williams, but he'd cost at least one of their second-round picks plus, and I'm not sure how that would work out cap-wise.

So Pace is in a tough spot.

This is supposed to be a great draft up front so maybe now we know those two second-round picks will both be big uglies.

But what really concerns me is the possibility that, having not added even a single body for depth and/or competition, Pace and Nagy might think they're OK up front just by replacing O-line coach Harry Hiestand with Juan Castillo.

I had no history with Hiestand prior to his coming to the Bears other than hearing from multiple sources that he is one of the best in the business at his craft.

That he got Charles Leno and Cody Whitehair to the Pro Bowl in his first season here, albeit as alternates, speaks volumes about him.

Whitehair maybe, but Leno?

According to several sources, Hiestand and Nagy just weren't a perfect fit together.

While that is reason enough to make a change, it's certainly no excuse to throw Hiestand under the bus, which is kind of how this is starting to feel.

Castillo is an accomplished, veteran offensive line coach with plenty of history with Nagy. But he didn't play to rave reviews in Baltimore or Buffalo after leaving Philadelphia, was out of the league last year, and I haven't been able to find anywhere near the number of admirers that line up for Hiestand, anxious to vouch for Castillo.

What I am hearing is he may be a bit too crusty for some folks' liking.

Hear me! I'm not saying Castillo is a bad coach; let's give the guy a chance. I am saying I believe Hiestand is a really good coach, and it feels like the Bears may be looking in the wrong place for answers while not taking their real issues on the offensive line seriously enough.

• Hub Arkush, the executive editor of Pro Football Weekly, can be reached at harkush@profootballweekly.com or on Twitter @Hub_Arkush