Five questions as the Vikings report to training camp

1. Who will start on the offensive line?

The wide-open competition along the line figures to be the most heated of the summer. Matt Kalil and Alex Boone are penciled in as starters on the left side. But there is uncertainty at center, right guard and right tackle. John Sullivan, who has returned to the field after two back surgeries in 2015, will try to reclaim the center job from Joe Berger. Brandon Fusco and Mike Harris will compete at right guard. And Andre Smith is the clear front-runner at right tackle after the sudden retirement of Phil Loadholt. There's probably a solid offensive line in there somewhere. It's up to new position coach Tony Sparano to find the best combination of…