With Rob Gronkowski retired, 49ers' George Kittle climbs ranks of NFL's top tight ends

Arguably the greatest tight end of all time, Rob Gronkowski, now is just a former football player.

Who will replace him as the king of tight ends?

One player on the list is the 49ers' George Kittle, who had a breakout season in 2018, actually surpassing Gronkowski's NFL record for most receiving yards in a season. But he's not at the top of the list - yet.

Gronkowski, 29, retired March 24. The former New England Patriot has two Super Bowl rings, and is the only tight end in NFL history to record at least 10 touchdowns and 1,000 receiving yards during the same season three times. But he played only 115 games during his career due to numerous injuries, such as a broken forearm, a torn ACL and a bad back which required multiple surgeries.

Gronkowski began to decline last season, when he recorded only 47 catches for 682 yards and three touchdowns. Lots of tight ends around the league, including Kittle, outperformed Gronkowski in 2018.

Here is a list of the best remaining tight ends in the NFL:

5. O.J. Howard, Tampa Bay Buccaneers: Howard was the 19th pick in the 2017 draft. He is only 24, and is one of the most physically talented tight ends to enter the league since the Patriots took Gronkowski with a second-round pick in 2010.

Howard played only 10 games in 2018 - he finished the season on the injured reserve list with ankle and foot injuries. And he had to share targets with three quality wide receivers - Mike Evans, DeSean Jackson and Adam Humphries. Still, Howard averaged 16.6 yards per catch, 56.5 receiving yards per game and caught five touchdown passes. In two seasons with the Buccaneers, he has caught 11 touchdown catches. He's a scoring threat in the red zone and a big-play threat in the middle of the field.

And he's improving. If Howard stays healthy next season, he could become a focal point of the Buccaneers' passing game and climb this list.

4. George Kittle, 49ers: Kittle already is the focal point of the 49ers' passing game. He was their leading receiver in 2018.

Kittle, 25, is a year older than Howard, and was a fifth-round pick in 2017. Zero draft experts expected Kittle to outperform Howard in the NFL. Yet so far, Kittle has done just that. In 2018, Kittle set the NFL record for most receiving yards in a season with 1,377, surpassing the mark Travis Kelce had set earlier on the final day of the season - when Kelce surpassed the mark held by Gronkowski.

Kittle blocks well, but performs his best with the ball in his hands. Last season, he led the NFL with 850 yards after the catch.

But Kittle caught only five touchdown passes in 16 games last season. And he caught merely two touchdown passes in 2017. He struggles making catches in traffic, which is why he hasn't become a weapon in the red zone.

If Kittle drops fewer passes next season and scores more touchdowns, especially in the red zone, he could become the undisputed best tight end in the NFL.

3. Eric Ebron, Indianapolis Colts: Ebron has been in the NFL for five seasons, but is only six months older than Kittle.

The Detroit Lions took Ebron with the 10th pick in 2014. He did not distinguish himself during the first four seasons of his career. But in 2018, Ebron signed a two-year contract with the Colts and immediately became one of the best red-zone targets in the NFL. He caught 10 touchdown passes in the red zone last season - Kittle caught just two.

Ebron is elite at making leaping, contested catches over linebackers and safeties. He is one of the main reasons the Colts made the playoffs in 2019. If he catches more than 10 touchdown passes again next season, he could solidify himself as one of the top three tight ends in the NFL.

2. Zach Ertz, Philadelphia Eagles: Unlike Ebron, Kittle and Howard, Ertz is in his prime now. He's 28. He probably won't get much better.

But Ertz doesn't have to get much better. He already is a go-to guy for a Super Bowl champion. Last season, he caught 116 passes for 1,163 yards and eight touchdowns. He led the Eagles in all three statistics.

Even though Ertz may not improve athletically next season, his numbers might if Eagles quarterback Carson Wentz stays healthy for the entire season. Wentz missed eight games the past two seasons. Ertz is far and away his favorite target, partially because Ertz is so reliable. He caught a whopping 74.4% of his targets last season.

1. Travis Kelce, Kansas City Chiefs: Kelce, 29, has been the NFL's best tight end since 2017.

That season, he caught 83 passes, while Gronkowski caught 69. Then, in 2018, Gronkowski declined and Kelce had the best season of his career. He caught 103 passes, scored 10 touchdowns and gained 1,336 receiving yards - second most by a tight end in a single season. Second to Kittle.

Kelce is good at everything. He blocks, makes contested catches over the middle, runs well after the catch and scores in the red zone. Last season, he gained 569 yards after the catch (second most among tight ends after Kittle), and caught nine touchdown passes in the red zone (second most among tight ends after Ebron). He will wear the crown as the NFL's best tight end until someone takes it away from him.