Lessons learned for Dallas Cowboys

IRVING, Texas – The Dallas Cowboys' offseason came to an official end Thursday with the close of the mandatory minicamp. So, it's time to ask, what have we learned over the last month?

While many players will continue to work out at Valley Ranch through early July, the next time the full squad gets on the field will be July 21 for the first day of training camp practice in Oxnard, Calif.

Here are five things that we learned during OTAs and the minicamp:

Dez Bryant prepped for monster year

Over the second half of the 2012 season, the only wide receiver who might -- might -- have been better than Bryant was Calvin Johnson of the Detroit Lions. Bryant has set some lofty goals for himself this offseason, but they don't seem too outrageous after what he accomplished this spring.

Bryant has always made great plays since he got to the Cowboys. Where he has improved is in his knowledge of the game and his understanding that there is always room for improvement. Bryant's on-field ascension has coincided with his off-field maturity. The Cowboys know things can change with one phone call, but they are confident Bryant is ready to break out.

All business: Monte Kiffin, Rod Marinelli

The Cowboys carefully studied the roster before hiring Kiffin as the defensive coordinator to make the move to the 4-3. They were convinced they had the pieces in place. The defense was all over the field during the minicamp, and the variety of players contributing was encouraging. Add a healthy DeMarcus Ware and Anthony Spencer into the mix when they open training camp, and they might be able to make the jump from average to one of the better defenses in the league.

Kiffin and Marinelli know how to get their points across without a lot of screaming and yelling. They may have simplified the defense, but they have raised the standard and challenged the players.

Travis Frederick will start at center

After drafting Frederick in the first round, the Cowboys talked about his position flexibility. However, since the first day of practice, Frederick has gotten all of the first-team snaps at center.

If Phil Costa is among the Cowboys' best five linemen -- better than Nate Livings, Mackenzy Bernadeau or Ronald Leary -- then that's the only way that Frederick would be moved to guard. Frederick's presence in the huddle grew as the practices went on, but he struggled some against Jay Ratliff and Jason Hatcher. There were also times, however, where he showed his strength as well as an ability to get to the second level.

When the Cowboys selected Frederick with the 31st pick in the draft, they did so with the belief that he was the final walk-in starter among the offensive linemen available on the draft board. They're not about to have him open the season as a backup.

Healthy and ready: Sean Lee, Bruce Carter

Lee ended the 2012 season on injured reserve because of toe surgery. Carter's breakout season ended early because of an elbow injury. But after Spencer's knee injury in minicamp last week, Lee and Carter were the best defenders on the field.

Lee picked up from where he left off last season when he made 77 tackles in six games. He was around the ball and active at his middle linebacker role. Carter's speed makes him a natural fit for the weak-side linebacker spot and he showed the ability to close quickly.

Lee and Carter could have been considered one of the best inside linebacker duos had the Cowboys stayed with the 3-4, but they'll also garner some recognition in the 4-3 if their offseason work is any indication of what they'll do in the regular season.

Bill Callahan will call plays on offense

The public acknowledgement of the move was clumsy, to say the least, but Jason Garrett said that this was the plan from early February on.

There will be an adjustment even as the offense remains the same. Playcallers have their own styles, and it will take some time for the Cowboys to learn Callahan's. He has the experience and he has playmakers, but the mechanics will have to be smoothed over.

On Day 2 of the minicamp, the first-team offense had a delay of game penalty and needed a timeout two snaps later. The situational work that Garrett likes to go through in practice will not only help the players, but it will help Callahan has well.