Josh Donaldson's season likely over after MRI reveals severe calf strain

Donaldson diagnosed with possible grade 3 calf strain, unlikely to return this season
Donaldson placed on 10-day IL with grade 3 right calf strain, could miss remainder of season
Injury occurred while running out ground ball, Donaldson's 2nd IL stint this year for leg issues
Despite disappointing season, Donaldson is established veteran with impressive career numbers
Yankees expected to use combo of prospects and veterans to replace Donaldson at third base