Seeing as it would have only been a short-term solution until Russell/Opacic/Blake/Sivo were fit again, Matterson to centre, and Cartwright into the side, would have been the most obvious choice, imo.
Cartwright can be defensively frail, true - but he is a genuine First Grader, and this option allows us to have the least amount of disruption to the side.
I'm not blaming Jake for our loss, because it simply wasn't his fault - but I don't think anyone can reasonably say he is ready for regular First Grade at this stage.