In Alan's perception, apart from Jose Porla, the eight leading figures all possessed S-Class combat strength. Seeing them made it clear to Alan that bringing them here was part of their plan all along. Once the Mages of Fairy Tail arrived, they intended to use their numerical superiority in S-Class Mages to wipe them out. That way, Fairy Tail's overall strength would take a massive hit, allowing other guilds to snatch up lucrative quests that originally belonged to Fairy Tail.
Furthermore, the timing of their strike must have been carefully calculated. Gildarts was away on a century quest and wouldn't be back anytime soon. Laxus and Ur had just left and wouldn't return quickly either. The only ones left in Ishgar were Alan, Makarov, Ultear, Erza, and Jellal. Makarov would certainly stay put to guard the guild and wouldn't deploy rashly. At most, they would only have to face the four of them. Meanwhile, the enemy boasted seven S-Class Mages, Jose Porla at the Wizard Saint level, and a bunch of low-tier A-rank Mages. They figured that sheer numbers alone would be enough to obliterate the four intruders.
Had Alan not tagged along, their plan might actually have succeeded, but these people would undoubtedly have all died here.
Chapter 129