PHILADELPHIA — The Eagles drafted Nebraska center Cam Jurgens with the 51st pick in the NFL draft Friday in an attempt to fortify their long-term depth on the interior offensive line. Jurgens, 22, was a three-year starter at center for the Cornhuskers and projects as the heir apparent for Jason Kelce. The 34-year-old is on a one-year contract and has contemplated retirement each of the last few offseasons. At 6-foot-3, 304 pounds, Jurgens compares favorably to Kelce in size and athleticism. He ran a 4.92-second 40-yard dash, and his 1.71-second 10-yard split was 90th percentile. His size and 3…