When you think of the prototypical power forward, the classic power forward, the total package as a power forward and then some, Karl Malone is exactly that. When you are talking about a man who was 6'9 255-260 pounds, with the quickness and shooting ability of a power forward and the physical strength of a center. He would've dominated at either position, but not being much of a shot blocker, better suited at playing the big forward, than playing center, at least playing center full-time. He was The Mailman because he delivered basically all of the time for the, I still feel strange saying this, but the Utah Jazz.
Malone put the Jazz on his back and carried that team his entire career. He was the only great and big scorer on his team almost his entire career. The only great rebounder and perhaps even good rebounder on his team throughout his career and the only great big man for the Salt Lake Jazz as I prefer to call them that the Jazz have ever had. And yet they were a title contender throughout the 1990s. And John Stocton was a big part of that as far as quarterbacking the Jazz being the great point guard that he was. But if Karl has a bad night offensively and they are playing a good team, the Jazz probably lose.
To go back to my point about the prototypical power forward, The Mailman was exactly that. He and Elvin Hayes might be the top two pure power forwards of all-time. Charles Barkley was more of a hybrid forward, someone with great skills at both the power forward and small forward. And I believe a better all around player than Karl and perhaps the best height for height rebounder of all-time at around 6'5. But Karl was exactly what you want from your power forward and then some. Tall, big, strong, quick, great inside scorer, great rebounder and an excellent defender and passer in the post.
Karl Malone was called The Mailman, because he was exactly that. He delivered for the Jazz time and time again and took them as far as he could almost by himself in the 1980s and 1990s. And perhaps just a few plays away from winning at least one NBA Finals in the late 1990s against the Chicago Bulls. Had the Jazz had a great swingman, small forward or shooting guard or good if not all-star caliber center to go with Malone and Stocton, maybe they would've won two NBA Finals in the late 1990s, instead of none. But they got very far with The Mailman delivering as much as he could.