Semien has been diagnosed with a Grade 3 left hip flexor strain and is expected to be sidelined 4-to-6 weeks, at minimum, Jon Heyman of the New York Post reports.
Semien initially tried to play through the injury, but it was too debilitating and he eventually landed on the 10-day injured list last Thursday. While the 35-year-old infielder is sidelined, the Mets will continue to use Brett Baty as their primary second baseman, with Ronny Mauricio also in the mix for some starts.