Three things that must happen for the Lions’ offense to be effective.

1. Quarterback Matthew Stafford must stay healthy. After shoulder surgery, he strengthened his upper back through rehab which should make him stronger and able to take big hits and still get up.

2. Wide receiver Titus Young and running back Mikel Leshoure — both rookies — need to learn the offense and learn it quickly once training camp starts. Both have worked one-on-one with Stafford during player workouts which gives them a jump on the situation. But since they haven’t had the luxury of OTAs or minicamps, they will naturally be a little behind the veterans.

3. The offensive line must be solid. Right guard Stephen Peterman, who was playing on a wonky foot most of last season, is healthy which should help. Right tackle Gosder Cherilus, who is coming off microfracture knee surgery, expects to be 100 percent for the start of training camp.

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