Tony Moeaki missing practice is always a concern given his injury history but this one appears to be something the Kansas City Chiefs knew about. According to several reports , Moeaki did not participate in Tuesday's practice, the start of the Chiefs 3-day minicamp. The only Chief not to do so.
Back in March, the KC Star reported that Moeaki had offseason arthroscopic knee surgery and that he was expected to return for OTAs, which begin on May 14. That would likely be why he's not practicing on April 16.
This is the final year of Moeaki's rookie deal and with the Chiefs signing Anthony Fasano to a multi-year deal this offseason it makes it all the more important for Moeaki to turn in a good season. If he will be back in May, it sounds like it's not a major issue. Although you have to consider his history.