Pro football can be simple. Offenses create. Defenses react. It's a 17-week cycle that grows even more dramatic when the playoffs begin.

A year ago, the New England Patriots, coming off a Super Bowl victory, had an offensive style that didn't draw the total attention of defensive coordinators. Brilliant Patriots offensive coordinator Charlie Weis used three-, four- and five-receiver sets in 2001 and didn't ask quarterback Tom Brady to throw more than 15 yards downfield.

Some defensive coordinators looked back at the 2001 stats and noted that Brady had some low-rated games late in the season. They were wrong. The offense run by Brady and coordinated by Weis started a trend. More teams worked the short passing offense to perfection and exposed secondaries that lacked speed.

Which brings us to this offseason and how teams reacted. They did react to find solutions to the short-passing offenses. They've studied the stats, crunched the numbers and came up with roster solutions for pass defenses and updates on other trends during what has been an interesting offseason.

Here are 10 trends that have developed:

	Jones

1. Safety issues: Perhaps the most interesting roster trend involved free safeties. There have been 14 changes so far at free safety with potentially more as competition heats up during training camp. It's not surprising teams have gone younger at free safety. That's a natural trend in the salary cap era. But with free safeties being the roaming quarterbacks of the defense, it was interesting to watch how teams emphasized getting more speed and range at free safety. Big money was spent by the Falcons (Cory Hall), Saints (Tebucky Jones) and Arizona (Dexter Jackson) to get speedier players at free safety. Other teams are trying to turn cornerbacks into free safeties -- Jason Sehorn (Rams), Dwight Smith (Bucs), Ryan McNeil (Chargers) and Corey Fuller (Ravens). The Redskins believe they stole one of the league's fastest free safeties by signing former Packers restricted free safety Matt Bowen. Defenses with two slow safeties were completely picked apart. Ask the Saints, Steelers, Chargers and others. Quarterbacks such at Brady, Rich Gannon of the Raiders and others picked apart gaps in the middle of the secondary and never stopped. But did teams overdo the process. Taking cornerbacks and putting them at safety could weaken the team's ability to tackle and draw plays could become a problem. Also, the once proud position of strong safety is going through a nasty overhaul. Eleven veteran strong safeties had to sign for the NFL minimum and others such as Blaine Bishop, Devin Bush, Anthony Dorsett, Victor Green, Keith Lyle, Marcus Robertson and Sam Shade still looking for work for this season.

2. Nickel for your thoughts: The other main emphasis was the shuffle to improve the third cornerback position. The Titans' defense, playing in a division filled with three-receiver offenses, had to be in nickel 66 percent of the time. Donald Mitchell, a third cornerback for the Titans, had nine starts and was on the field 55 plays a game. Though he wasn't a starter, situational substitution made him the equivalent of having starting status, which enhanced Mitchell's value and landed him a three-year, $2.715 million contract in Dallas. At least 22 teams toyed with presumed upgrades of their third and fourth cornerbacks. Who did the best? My votes go to Atlanta, Dallas and Seattle. What used to be a weakness for the Cowboys has turned into a strength. With first-round choice Terence Newman, Derek Ross, Mario Edwards and Mitchell, the Cowboys have four quality coverage cornerbacks. The Seahawks could survive with Shawn Springs and Ken Lucas, but adding Marcus Trufant as a third cornerback gives them a great chance to face the passing offenses of Jeff Garcia of the 49ers and Kurt Warner of the Rams. The Falcons robbed the Packers for a starting cornerback (Tyrone Williams) and a third cornerback (Tod McBride). Other interesting additions include Tyrone Poole going from Denver to New England and Terrell Buckley going from New England to Miami to challenge Jamar Fletcher as the Dolphins third cornerback.

	Price

3. Money matters at receiver: On the offensive side, two classes of wide receivers are evolving financially. The difference is becoming more distinct because of increasing salaries. A team's top receiver, the supposed "go-to" guys, land contracts in excess of $5 million a year. There are now 13 such receivers drawing top dollar, and Torry Holt of the Rams should be added if he gets his $6 million a year deal before the start of training camp. The second best receiver on a team gets between $3 million and $4 million a year if they are good. That causes a problem for good, young receivers entering the prime free agency years. It forced the Bills to trade Peerless Price to Atlanta because it was tough to give him more than $3 million a year when they have Eric Moulds signed to a six-year, $38.2 million contract. Darrell Jackson of the Seahawks is taking the chance he can land No.1 receiving money by signing a one-year restricted tender.

4. Setting a trend: Mike Shanahan of the Broncos is hopefully starting the trend of the future -- the player-coach. He's taking talented third cornerback Jimmy Spencer and giving him assistant coaching duties. Spencer is like a lot of good veteran cornerbacks. He teaches young corners while he's playing, so it was only natural for him to move toward coaching. The only problem is that Spencer is still good enough to play in the nickel and intercept a few passes. Last year, Spencer gave a lot of pointers to teammates during practices and watched them execute better on the field. There are a lot of Jimmy Spencers in the NFL, and Shanahan has come up with a unique way to exploit all of his talents -- as a player and a coach. Teams will watch this experiment and hopefully they will copy. Spencer is the league's first player-coach since Dan Reeves. He better not be the last.

	Fiore

5. Movement in the middle: Top centers can make $4 million a year, being paid at the level of the league's best guards or on a scale with some of the league's better tackles. What was interesting about this offseason is how teams didn't throw a lot of money at the center position. The Redskins are considering taking guard Dave Fiore and moving him to center. Tom Ackerman is making a similar move for the Titans. Brad Meester is making that move in Jacksonville. Mike Goff is doing the same in Cincinnati. It's an interesting transition. Many teams love building their lines from the outside in. They will pay big money to the two tackles and maybe a center, opting to save money for less expensive veteran guards. With 27 teams in the 4-3 defensive alignment, centers aren't always matched up against a nose tackle, so teams believe they can create a center by taking good guards and making the switch. It's been a trend evolving over the past couple of years.

6. Glory to the MLBs: Middle linebackers are no longer just run-stoppers. Thanks to the unique range and skills of Ray Lewis, Brian Urlacher and others, the middle linebacker continues to enjoy its greatest days since those of Dick Butkus. With so much nickel defenses, teams only need to keep one or two linebackers on the field, but more teams are putting their money in middle linebackers and keeping them on the field during passing down. There have been a dozen moves this offseason at middle linebacker. Kevin Hardy of the Bengals, Mike Peterson of the Jaguars, rookie first-rounder Nick Barnett of the Packers could earn three-down responsibilities. No longer do defensive coordinator stereotype linebackers as outside or middle. They don't fear taking a mobile linebacker who played mostly on the outside and put him in the middle of the action. That may not work if the team doesn't have two good defensive tackles who can protect the middle linebacker from being blocked by guards or centers. Still, it's good to be a middle linebacker.

	George

7. Running towards empty: Perhaps the most interesting trend to watch over the next year is what will happen with the game's best halfbacks. Eight starters enter the season in that dangerous age of 30 or older and Stephen Davis, Corey Dillon, Priest Holmes and Eddie George are a birthday away from being 30. Historically, a running back's stats start to fall as he crosses the 30-year mark. Better conditioning and smart coaching might prolong the moment, but for how long? There are clearly not enough top young running backs to replace the great ones who might be gone in the next few years. This year's draft class is filled with either questionable talent or guys coming off major injuries. It may be a league that has gone pass crazy, but great running games put teams in the position of making the playoffs year in and year out. Stay tuned.

8. Fullbacks cash in: It was strange to see what was going on at the fullback position. Usually, fullbacks are only the field about 18 percent of the offensive plays. Though these guys are true warriors and are clearly unappreciated, there was some question about what direction the position was heading. Well, this offseason, a dozen veteran fullbacks received multi-year contracts, and seven received contracts worth around $1 million a year or more. Fullbacks are designated hitmen for offenses. They line up in front of the halfback and their job is to blast holes in the blocking scheme. While they may not get a carry every week, some, particularly those in the West Coast offense, get involved in the passing game. It was great to see a number of fullbacks get some long-term security at a position in which a player sacrifices their body so much. Still, it will be interesting to see if they get more playing time this season.

9. Spotlight on young DTs: This will be a transition year for defensive tackles. Twenty four were drafted, including six in the first round and 12 in the first four rounds. Initially, only a few are projected as starters -- Ty Warren in New England, Dewayne Robertson with the New York Jets, Kevin Williams in Minnesota and Johnathan Sullivan in New Orleans. Will the transition be fast or slow? The league is loaded with 300-pound plus defensive tackles who have been around for a long time. Great training camps by the drafted defensive tackles could spell doom for a lot of big name starters. There has been a theory that it's hard for 300-plus-pound defensive tackles to last until their mid thirties, but several have defied the odds.

10. Money management: It's taken a decade but teams have found the right way to manage salary caps, and that will have a significant impact on free agency in future years. It allows more teams to have the luxury of giving contract extensions to their best young players, resulting in fewer stars hitting the market. Look at the limited June salary cut market. Only a dozen veterans were cut in June -- the least ever -- and that has only put $20 million of dead money into the 2004 cap. That frees up more money in 2004 cap to spend on free agents even though the quality of the class might be done. As summer begins, there will be only about 110 starters who will be free agents as unrestricted free agent or players whose contract voided. There are 25 teams with more than $2 million of cap room, so more starters will sign extensions. To date, only seven teams are over next year's cap. Teams have the freedom and luxury to decide. If they want players, they can keep them. It's an interesting trend.

John Clayton is a senior writer for ESPN.com.