Ravens defensive tackle Michael Pierce appeared on the field briefly Tuesday for the beginning of mandatory minicamp but departed because “he’s not ready to practice from a safety standpoint,” coach John Harbaugh said.Pierce, who played at a listed 340 pounds in 2018, appeared to have put on significant weight since the end of last season. He did not participate in the Ravens’ voluntary organized team activities the previous three weeks.“For his own health and safety,” Harbaugh said when asked why Pierce departed practice. “We recognized that, and we pulled him off. … He’s not ready for this practice yet, as you can probably tell.”Harbaugh said the 26-year-old Pierce has yet to take his required conditioning test, which he’ll have to pass before practicing during training camp next month. Most players on the team have passed the test, though they’re not required to meet that standard to participate in minicamp.This is an important year for Pierce, who’s heading toward unrestricted free agency next offseason. He was the Ravens’ top-graded defender in 2018, according to the scouting website Pro Football Focus. And if he repeats that performance, the former undrafted free agent could be one of the most sought-after interior linemen on the market.Despite his natural bulk, Pierce has never faced concerns about conditioning heading into his previous three seasons with the Ravens.“Oh sure, it’s a problem,” Harbaugh said. “We want guys practicing. We want them ready to practice and physically able to practice. It’s very important.”The good-natured Pierce is among the most popular holdovers from last season’s top-ranked Ravens defense.“I can’t wait to see him back here and just to be playing alongside my brother again,” fellow defensive tackle Brandon Williams said last week. “I expect big things out of him. I told him — we did a little Twitter thing — I told him, ‘Let’s get paid this year. Let’s go out there and ball out and get the bag.’ Everybody wants that second contract, so let’s get him one.”