ALLEN PARK -- The Detroit Lions opened their three-day mandatory minicamp on Tuesday. Here are some notes and observations from the two-hour workout.

-- After skipping conditioning and OTAs to spend more time with his family in Houston, Glover Quin returned to Detroit on Monday and was suited up for practice a day later. In fact, everyone except receiver Andy Jones was accounted for in Allen Park. But not everyone was participating fully. Offensive lineman Joe Dahl and safety Tavon Wilson were in red no-contact jerseys, while defensive end Ezekiel Ansah continued to do almost nothing. And tight end Hakeem Valles did nothing at all.

-- While some wondered whether the Lions could target a cornerback in free agency, GM Bob Quinn said at the combine that long-term solutions could already be on the roster in youngsters like Teez Tabor and Jamal Agnew. On Tuesday, we got a long look at exactly what he meant. Tabor was working with the starters at the outside cornerback post opposite Darius Slay, while Agnew was the No. 1 slot. It's hard to say exactly how they did because much of their work was done about 50 yards from the bleachers where Detroit pens in reporters these days, but Tabor did look like he had a good day, and even picked off Matthew Stafford. He just might be the odds-on favorite to start Week 1, supplanting Nevin Lawson. Agnew will have more competition in the slot, where Lawson and DeShawn Shead are also possibilities. But his speed is undeniable, and his game is coming along. It really showed on one play where he blanketed Golden Tate on a pass along the left sideline, forcing an incompletion.

-- Detroit says Frank Ragnow doesn't have a position. I beg to differ. Ragnow hasn't taken a rep at center during the two full practices open to reporters this offseason, and photos and videos posted by the team show him repping at guard then too. At this point, he's a guard, Graham Glasgow is the center, and it's a good bet Detroit will open the season that way against New York.

-- Nick Bellore's move to fullback is complete. I mean, it was already complete in OTAs, when he was wearing a white jersey with the rest of the offense and working exclusively at fullback. But he was still listed as a linebacker, the position he played his first six seasons in the league. Now he's actually listed as a fullback too, and was actually repping ahead of Nick Bawden, the guy drafted in the seventh round to play the position. It seems not only will Detroit bring back the fullback, but it has actual competition there too. And if these early practices are any indication, Detroit plans to run a whole lot of two-back sets.

-- The best moment in practice had to be when Sam Martin boomed a punt on the field nearest the media -- then watched the ball drill a staffer right in the chest about 60 yards away. Yeah, there's nothing wrong with his foot these days.

-- Jamal Agnew, Golden Tate Brandon Powell and Teo Redding were the guys I saw shagging punts. No Ameer Abdullah this week, after he got in some work there during the first round of OTAs.

-- Levine Toiolo got the first tight end rep during full team drills, but Luke Willson was the first guy up in other drills, and Michael Roberts led individual drills. There's no telling who will start at this point, and given their varied skill-sets, it could change week to week. Willson is the fastest and rangiest pass-catcher, Toiolo looks like the most physical blocker, and Roberts is somewhere in the middle.

-- Matt Cassel supplanted Jake Rudock as the second-team quarterback, after Rudock had gotten all those reps during the OTA that was open to reporters. It'll be interesting to see what happens here Wednesday and Thursday. Perhaps Detroit is rotating those reps, to see who handles the assignment better. Or, perhaps, Cassel gets all the second-team work the next two days, indicating the veteran is already passing Rudock on the depth chart.

-- Matthew Stafford was mostly sharp on Tuesday, including threading nice passes to guys like Golden Tate along the sideline and a sliding Marvin Jones over the middle. He hooked up with Michael Roberts for a beautiful play with Miles Killebrew in coverage, and squeezed a pass to Luke Willson between a trio of defenders. But he wasn't perfect either, including throwing the pick to Teez Tabor and also hitting a paddle that assistants hold up at the line of scrimmage to squeeze passing lanes.

-- Every practice seems to reveal a new drill or two in the Matt Patricia era. On Tuesday, the most interesting one occurred with the linemen. Offensive and defensive linemen would face each other gripping what looked a lot like a steering wheel. The drill seemed to be designed to work on hand placement and leverage.

-- Receiver Dontez Ford headed indoors with a trainer toward the end of practice.