Sark would probably tell you it's a little of both. I'll lean more toward a lack of options.
Klare is/was redundant with Niblack, which made it easier for the staff to move on from him, IMO. Either way, Texas would rather be in a position of trying to make the pieces fit than being one injury away from being in a bind.
What I was thinking of when I wrote this was from the perspective that there might not be a suitable option in the portal. Rather than reach for someone to improve the numbers, I'd rather Sark double down on playmaking ability at either RB or WR to give Arch another weapon.