Siby is likely a new name to many in the United States, but is well known overseas. He has played in various leagues over the last three to four years. During the 2023-24 season in Belgrade, he averaged 12.1 points, 8.6 rebounds, 1.6 assists, 1.5 steals and 2.5 block in 25 minutes per game while shooting 65.8% from the floor, 33% from three-point range and 62.8% from the free-throw line. During the 2024-25 season across various Serbian leagues, he averaged 9.4 points, 5.9 rebounds, 0.4 assists, 0.8 steals and 1.4 blocks in 22 minutes per game while shooting 64.2% from the floor and 69.2% from the free-throw line. During the 2025-26 season across various Serbian leagues considered to be a higher level than previous years, Siby averaged 3.6 points, 3.2 rebounds, 0.5 assists, 0.3 steals and 1.1 blocks in 13 minutes per game while shooting 62.5% from the floor and 81.5% from the free-throw line.