The 49ers had Vernon Davis and Delanie Walker, and they came within five yards of winning the Super Bowl.

The Patriots have Rob Gronkowski and Aaron Hernandez, and they have the NFL’s most prolific offense.

The Ravens armed Joe Flacco with Dennis Pitta and Ed Dickson, and he just won it all and became Super Bowl MVP.

Two tight end offenses are sprouting across the NFL landscape, becoming the preferred strategy of offensive-minded coaches. It’s about to become a staple of the Eagles’ offense, with Chip Kelly calling the shots and with two 28-year-old tight ends -- Brent Celek and James Casey -- in his arsenal.

“We're definitely going to use both him and Brent in the game at the same time,” Kelly said Wednesday during a press conference that introduced Casey and defensive tackle Isaac Sopoaga as new free-agent signings.

“I think there's a lot of that going on in the league right now. You just look up the road at the Patriots using Gronkowski and Hernandez at the same time. I think the mismatches that they create sometimes, they're too athletic for linebackers and they're too big for defensive backs, and it's big man's game, and when you can get big, athletic guys that can run, it's our job as a coaching staff to put them in position to make plays.”

Casey, a fullback/tight end hybrid, is coming off the most productive season of his four-year career with the Texans, catching 33 passes for 340 yards and three touchdowns. But he and the Eagles think Casey has only scratched the surface of his pass-catching potential.

Casey once caught five passes for 126 yards and a touchdown in a 2009 game against the Saints and finished that year with a seven-catch, 91-yard effort against the Titans.

The opportunity to shed the fullback label and emerge into a field stretcher in Kelly’s cutting-edge schemes prompted his bolt from Houston, a playoff team for the past two seasons, to the last-place Eagles just a few hours into the free-agent signing period.

“For me personally, what sold me is just looking at his past and everything that he's done at the college level in his career,” said Casey, a renowned athlete who played seven different positions in college at Rice after giving up on his baseball career.

“Obviously, what he's done speaks for itself. And then what he's going to bring to the Eagles, I thought it's really exciting, and I know that the team didn't have the greatest ‑‑ they didn't have what they wanted to do last year -- but I know there's a lot of great players when you look at the roster.

“That was the main thing, that I thought it was best case for me to come here and to get an opportunity to see my full potential as a player, because as a player you know you work hard but you want to give yourself a chance to see what you really can do and give yourself the best opportunity to succeed, and I think this is it for the team and for myself.”

Kelly has visited Bill Belichick’s practices in New England and has shared some of his ideas and concepts with the three-time Super Bowl head coach. He’s dropped several hints since being hired in January to replace Andy Reid that the design of his offense will bare resemblance to New England’s.

The Patriots led the NFL in offensive points, total offensive plays and in tight end production. Gronkowski, who battled injuries much of the season, still led NFL tight ends with 11 touchdowns and caught 55 passes for 790 yards, averaging 14.4 yards per catch. Hernandez added 483 yards on 51 catches and five touchdowns.

Hernandez also has nine career carries and has lined up in multiple positions, a skill set that compares to Casey’s.

“I think the versatility that you can present to defenses is when you have a certain grouping in a game that's not only one thing you can do,” Kelly said, “and I think the teams that have been successful doing it, you know, when you watch the Patriots line up Aaron Hernandez all over the place -- is he going to be at tight end, is he going to be at receiver, is he going to be at running back? It makes it very difficult for the defense. They don't know at the beginning of the play where people are going to line up and what they're going to do. It keeps them on their toes.”

Celek has never made the Pro Bowl and his reception totals have fluctuated because of offensive line struggles that required him to stay back and block, but he’s never caught fewer than 42 passes in any of the past four seasons and has three seasons of 55-plus receptions in the past four years.

Celek’s 12 yards per catch last year was seventh-best among tight ends with at least 30 receptions, and his 1,531 yards-after-catch total since 2009 are the most by any NFL tight end. He ranks second in franchise history with 280 receptions and 3,473 yards.

Casey has only 66 career receptions but has averaged 11 yards per catch and has receptions of at least 30 yards in each of his four seasons. His athleticism is through the roof; after leaving pro baseball to play football at Rice, Casey started his his career at linebacker before moving to defensive end and then moving again to the offensive side.

“Extremely versatile, and one of the qualities we really liked about him,” Kelly said. “He was only in college for two years, but that kind of versatility really shines when you see him play on tape. Played fullback for the Texans, played tight end for the Texans, played slot receiver for them.”

“So as a coach it's almost like you kind of got a new toy when there's a lot of different spots you can put him in because he's got a background in it and he's extremely smart, extremely intelligent.”