Being a goalie is an important role in the NHL. Many factors of a game rely on the ability of the goalie. If a starting goalie is injured, it is dire to have an efficient player replace him, and do it well so the general manager, coach, team and fans have confidence.
The back-up goalie is just as important as the starting goalie.
One such example is the current issue in Montreal. Carey Price is an exemplary starting goalie. He was injured and the entire fan base of Montreal cringed. But Michael Condon stepped in to take the role of backup and Montreal is still holding first place in the Atlantic Division due to Condon's strong performance. The team hasn’t wavered. Goaltending is highly depended on. Montreal supporters are still confident.
In Philadelphia, there is a similar problem of two dependable goaltenders: Steve Mason, the starter, and Michal Neuvirth, the backup.