With Rob Gronkowski out, now what for Patriots offense?

Life without Gronk.

This is not a new experience for the New England Patriots, but the latest injury has the potential to derail the franchise’s hopes for Super Bowl LI.

Tight end Rob Gronkowski, easily the team’s most indispensable player aside from quarterback Tom Brady, will undergo back surgery on Friday to repair a herniated disk. The Patriots said in a statement late Thursday night that they do not expect him to return this season, though they will wait until after the surgery to make that determination.

The Patriots must now regroup and adjust. Gronkowski is not only New England’s most dangerous pass-catching threat, he’s also a dependable blocker in the running game.

The injury instantly makes tight end Martellus Bennett, who was acquired in an offseason trade, an essential player. Bennett is a reliable pass catcher (42 receptions, 540 yards, four touchdowns in 2016), but three of his scores came in a Week 5 game against the Cleveland Browns.

Bennett is solid, but not on the same level as Gronkowski.

And what made Bennett most effective in New England was Gronkowski’s presence.

Consider this: In the three games Gronkowski has missed this year with hamstring and lung injuries, and a Week 3 game in which played only 14 snaps largely as a decoy, Bennett has caught only 13 passes for just 160 yards and one score.

If you remove Gronkowski (25 catches for 540 yards, and three scores this season) from the offense, Bennett isn’t as difficult to defend.

This also means New England’s trio of running backs – LeGarrette Blount, Dion Lewis and James White – need to increase their production, especially in the passing game.

Patriots' Rob Gronkowski to have back surgery, season likely over

Both Lewis and White excel at catching passes and can be shifted along New England’s formations. Look for offensive coordinator Josh McDaniels to line both players up along the slot and even outside the numbers to give the Patriots mismatches they can exploit.

Another thing to consider is the Patriots defense, which has shown some weaknesses this season. If the offense can no longer be expected to put up big numbers, that puts more pressure on the D. That is not a good thing for the Patriots.

Even if New England does make it to the Super Bowl, and even if Gronkowski is cleared to return, he may not be as effective as usual.

A quick history lesson:

• In January 2012, Gronkowski suffered a sprained ankle in the AFC title game that later required arthroscopic surgery. Though he hauled in an NFL-record 17 touchdown catches by a tight end that season, the hampered Gronkowski caught only two passes for 26 yards in New England’s 21-17 loss in Super Bowl XLVI.
• In both 2012 (broken forearm) and 2013 (torn ACL, MCL), New England suffered defeats in consecutive trips to AFC Championship games and sorely missed Gronkowski’s production.
• In 2014, the Patriots beat the Seahawks in Super Bowl XLIX using a healthy Gronkowski as a key weapon.

Last season, a knee strain in Week 12 forced New England to limit Gronkowski down the stretch. The Patriots lost three of their last five games and ceded home-field advantage to the Denver Broncos, who beat New England in the AFC title game.

According to NFL research, since 2010, Tom Brady’s passer rating is 20.1 points higher when Gronkowski is in the lineup. Over that span, Brady completes 8% more of his passes, throws for 33 more yards per game – but most important, the Patriots win more games when Gronk suits up. New England has gone 69-17 (.802) over that span with a healthy Gronkowski, compared with 12-5 (.706) when he misses games.

This is Gronkowski’s third back surgery in his career. He has missed games in five seasons in a row, 21 total in his career. And even though he’s only 27 years old and has been the most dominant tight end in recent history, this setback casts doubt about whether Gronkowski can be a consistent, dependable and injury-free player.

Follow Lorenzo Reyes on Twitter @LorenzoGReyes