It's appearance was changed during 2014 Xmas.Take 2 pairs that could possibly get a Soccer Dragon and you will have a higher chance of getting it. If you have a level 3 or 4 hatchery it is a smart idea to combine it with the Ultra Breeding Tree and the Breeding Mountain. This could help players who want more rare dragons like the Soccer Dragon for example.

Upgrading the Hatchery will not affect any on-going hatching. The Hatchery can be upgraded up to level 5 (can hatch up to 5 eggs at once). It can be moved, but it can't be sold or put in storage. The Hatchery is so important that it is the first thing you see during the initial tutorial. At the end of that time the new dragon may be sold or placed into a Habitat, a Kindergarten, or the Dragonarium. To hatch into a baby dragon every egg has a fixed amount of time it must spend in the Hatchery. All dragons start as eggs whether obtained by buying, breeding, receiving rewards, or receiving gifts. The Hatchery is a key structure in the Dragon City breeding process.

Dragon city breeding time chart