McMahon is out of the lineup for Tuesday's game against the Rays.
With a tough southpaw on the bump in reigning American League Cy Young winner Blake Snell, the lefty-hitting McMahon will retreat to the bench, opening spots on the right side of the infield for Mark Reynolds and Garrett Hampson and designated-hitter duties for Pat Valaika. Valaika will more than likely be the odd man out when the Rockies play in National League parks, while one of Reynolds or Hampson will likely give way to McMahon against right-handed pitching. McMahon should have a fairly clear path to a strong-side platoon role for at least the next month while top first baseman Daniel Murphy (finger) is on the 10-day injured list.