Brandon Pettigrew is a bit of a relic in today’s NFL, a tight end who’s just as comfortable blocking as he is catching the ball. For the Detroit Lions, that versatility was a part of their offense they couldn’t bear to lose. Pettigrew agreed to a four-year, $16-million deal with the Lions on Thursday that includes $8 million guaranteed. He’s en route to Detroit this morning to take a physical and sign his contract. One of the top tight ends to reach free agency, Pettigrew received serious interest from at least three other teams but in the end decided to stay with the franchise that drafted him in the first round out of Oklahoma State five years ago. Though he was coming off a down season statistically in which he caught just 41 passes for 416 yards, the Lions made retaining Pettigrew their No. 1 off-season priority at the position. A good blocker who had two 70-plus-catch seasons early in his career, Pettigrew fits the all-purpose mold new offensive coordinator Joe Lombardi likes in his tight ends. He’s missed two games each of the past two seasons with ankle injuries, but rarely came off the field when healthy last year, when he was used less than normal in the passing game because of other deficiencies at the position.