Let's do something fun with the pocket.
We're going to make a scalloped flap without removing the flap from the body of the jacket.

Remove the old patch pocket:

Remove any topstitching from lower corner to lower corner.
DO NOT REMOVE ANY EDGE (HIDDEN) STITCHING!!!
Fold the flap in half and stick a pin in the fold. This marks the point in the center of the pocket.
Fold the flap from each side to the center pin. Stick a pin in each fold. This quarter point marks the deepest part of the scallop.
With 3-5 tight whipstitches, baste right at the center pin:

Baste at each lower corner with 3-5 tight whipstitches:

Snip about 3/8" deep through the edge at each quarter-point pin.

Here's where the cool part starts:
With your finger, poke the edge up inside the flap itself.
A small mouth will form of that snip we made in the previous step as the scallop forms:

The inside seam allowance will try to roll upon itself. You need to massage it into place so it lies flat against the back of the face fabric.

Once you get everything inside laying flat, pin it in place and press:

You don't need to press it hard at this stage, but the steam will relax the seam allowance that was giving us a hassle in the previous step. If you're not happy with the shape of the scallop at this step, pull your pins and reshape it. It will be easier the 2nd try because of relaxing that seam allowance.
Deep press and blind stitch the edge of the pocket to the lining.

The magic is that by leaving the original edge stitching intact, by worrying about the face scallop into place, the lining automagically follows it and it's a scallop, too.
Re-topstitch and you're done.