*I'm going to assume you stole the diamond sign and replaced it with the bronze tier one for the "Helped a Star" Achievement as I don't think you can obtain this achievement without doing so.
For this achievement and I'm not sure if it's all needed but once you wreck his fame there is a small pipe on the side of his house that you can use the magnet power to climb up, from there link to the satellite and then to the top of the roof where you should see a dead Santa, loot his hat (part of Shelf Filled achievement) and drop down the chimney. You'll now be in the guys home, and can talk with him. Open the door to his house from the inside. Again I'm not entirely sure if this part is needed but it's what I had done.
Now if you tried shooting the yellow ball into the net using the pipe while the 4 Red's were here and the diamond sign was present above his door, they told you that's not how you become 3 tier diamond. So now try it while they are not there with the bronze sign above his door and shoot the ball into the net. You'll see the former champ say something to you and the achievement should unlock.
**Note, I had progressed the story a bit more finishing the carrot area before I came back to this map and took a shot at the goal with no Red's watching just for the hell of it.. At first I thought it had to be a field where people could see you sucking hence the achievement description, but since it doesn't unlock with them there I ran away to continue the game thinking this wasn't the spot. However, upon returning when the guy was alone it worked.