oh thats brutal, worst i have seen...cant fix that really without replacing the back wall...mark murrell can help you with this and he is the only one i know of
if you have read the other threads you have read about the epoxy route...both sides of the goal, i would smooth out the area, use the liquid hard nails next and get it to soak into the wood, let dry completely, get recommended epoxy, mold, fill, shape, dry, and then sand to spec and smooth it out, paint if wanted...
i am of the opinion, although I have not really shared this or tried it yet, that after doing all this, you take a high density laminant, perfer white, and cut a piece about 1 1/2 inches wide and as long as the straight side of the goal (before the curve)...the side facing the goal edge should be sanded to a 45 degree bevel to help prevent further damage...the top and outside long edge should be softened/rounded to create least impact if ball hits the edge...leave bottom flat
make sure bottom is flush with table surface (or within 1/8 to 1/16 from table surface) make four of these, two for outside, two inside
get very good fast drying glue and make sure the strips are smoothly and completely covered and applied - no air bubbles
not perfect but better than replacing the back wall...my other thought was the same as that but use metal - however, if u use white lam, you could put a real cool customized message on the stip like, Fire Enters Here