They set the machine to play at 2-ply, i.e., it only looks two moves ahead. It's not so surprising even a good algorithm would lose in 15 moves at 2-ply.
The article mentions they also played at 5-ply and it lasted 27 and 30 moves against Kasparov, which is probably better than most casual players would do.
The article mentions they also played at 5-ply and it lasted 27 and 30 moves against Kasparov, which is probably better than most casual players would do.