Cubs' Dansby Swanson left game due to wife's knee surgery.
Mallory Swanson was injured during a soccer match.
Cubs signed Dansby for his winning pedigree and durability.
Swanson chose Chicago for his wife's established career in the city.
Cubs erased a seven-run deficit against the Mariners.
Swanson signaled to the dugout before the start of the sixth inning.
Swanson's issue was described as "lower left side tightness."
Swanson felt physically tired and emotionally drained after wife's injury.
Swanson is hitting .400 with Gold Glove defense for the Cubs.
The couple is heartbroken but will get through it together.