Celtic, the Scottish Premier League side, has emerged as the top club in terms of average possession during their first phase of the season. This is evident from the league table, which shows that Celtic's team is averaging more than 65% of the total possession compared to the Scottish Championship leaders, Hearts.

The reason for this high average is attributed to several factors. Firstly, Celtic has been playing with a lot of intensity and determination throughout the season, resulting in a higher level of physicality on the pitch. The team's style of play, known as "Spartan Football," emphasizes attacking football, which demands a lot of physical effort and quickness from the players.

Secondly, Celtic's goalkeeper, David de Gea, has also played a significant role in improving their defense. De Gea has become one of the best goalkeepers in the world and his ability to intercept passes and make saves has helped keep teams at bay.

Furthermore, the team's midfielders have also contributed significantly to their performance. They have been able to create space for the forwards to move towards the goal, which has allowed them to score goals easily.

In conclusion, while there are many reasons why Celtic has achieved such success, it is clear that the team's style of play, combined with their hard work and dedication, has led to their dominance in the first phase of the season. As the season progresses, we can expect to see even more impressive performances from Celtic and other clubs in the Scottish Premier League.