Could 49ers’ non-contact Achilles injuries in Super Bowl be linked to practice field?

The 49ers had two bizarre injuries during the Super Bowl: Linebacker Dre Greenlaw tore his left Achilles while jogging from the sideline onto the field, and defensive backs coach Daniel Bullocks tore his while jumping up to celebrate an interception."It's crazy," coach Kyle Shanahan said Tuesday, via Matt Maiocco of NBC Sports Bay Area.While there is no evidence to link the injuries, the 49ers expressed concern about lower-body injuries because of the condition of the practice fields at UNLV. The team spent three days on the sponge-like fields after the artificial surfaces were overlaid with natural grass.The 49ers compared it to the turf at MetLife Stadium.Shanahan was asked whether the team has any theories about why both Greenlaw and Bullocks similarly blew out an Achilles."Nothing I want to get into," Shanahan said. "It's frustrating."Greenlaw is unlikely to be ready for the start of the regular season, 49ers General Manager John Lynch said Monday. The linebacker likely starts the year on the physically unable to perform list, which would make him ineligible to play the first four regular-season games.