I don't think many people realize that Stuart/Holden have been our #1 pair recently.
Stuart/Holden have been getting a lot more minutes than Hejda since EJ went down, and generally seem to get the toughest matchup.
That's only because of how Roy/Tourginy have been using the pairings with EJ out. They've spread out the minutes more, and Holden's getting more PP time.
They started out with Hejda-Redmond as the shutdown pairing with EJ out, but Redmond just wasn't capable of this, and Barrie wasn't a better option defensively. So lately they've been going with rotating pairings, using Hejda to spot fill on different combos.
If you have an opportunity to do so, go back and skim through the LA game. They'd stick with their regular pairings for a while, then shuffling them up for a couple shifts, then go back. Sometimes because of a PP, but they'd just keep going with it for a bit. Keeping the same mashed up combos coming out of a tv timeout when they had the opportunity to go back.
Hejda spent time with Guenin on a pure shutdown type of line, he also played with Stuart, he also played with Redmond and Barrie. Not just throughout the game, but from the puck drop in the first period. It was their game plan entering the game. He's using Hejda in multiple roles to help spot fill for the weak lineup. It's too much to ask of him, especially since he's likely still battling through that knee injury.
Holden's facing top lines on occasion because they need a capable puck mover to get the puck out of harms way, and this isn't Hejda's game, and they don't fully trust Redmond and Barrie defensively. Hence the Holden-Stuart combo as the only one that really makes sense in that fashion.
As Barrie has been better and better lately, I wonder if they'll start to test him defensively and go with a Hejda-Barrie top pairing soon.