Start by answering why projects need to be easier to deliver. Of course they should be, but the nuance of the answer is the thing you measure. You see something that indicates that they're "too slow." What impact would you see on the R&D team if the delivery team did better? Go back to why you have a delivery team at all.

Or you can ask in the reverse: when would you stop wanting to invest in delivery beyond maintenance? What does "good enough" look like?