Free agent Allen Robinson is the type of receiver that could help take the San Francisco 49ers’ offense to the next level.

His size (6-foot-3, 220 pounds) and explosiveness off the ground (39 inches in the vertical, 127 inches in the broad jump, both in the 87th percentile among receivers tested at the combine) bear out what he’s shown on the field. He’s one of the NFL’s best red zone targets.

Eighteen of Robinson’s 22 career touchdowns have come inside the red zone, where the 49ers scored touchdowns on 24 of 51 trips (47 percent), good for the fifth-worst mark in the NFL in 2017.

The red zone was one of the few areas the 49ers didn’t improve with Jimmy Garoppolo under center. In his five games, they converted 11 of 24 trips (46 percent) inside the 20. The key difference: They averaged 4.8 red zone appearances with Garoppolo compared to 2.5 with Brian Hoyer and C.J. Beathard.

But the red zone benefits Robinson could offer the 49ers might not necessarily be his most alluring traits, particularly for a team focused on the future like San Francisco.

Robinson is 24 (his 25th birthday is Aug. 24), making him seven years younger than the team’s current top wideout, Pierre Garçon, who will turn 32 during training camp. Robinson’s addition this spring would be about solidifying the future of the receiving corps as much as helping in the red zone in 2018.

The big blemish on Robinson’s free agency is the ACL tear suffered in the 2017 season opener. He missed the season and is still recovering, which could be why Jacksonville decided against giving him the franchise tag at some $16 million fully guaranteed.

But a case can be made that Robinson’s injury was a blessing in disguise for his next team if he tests the free agent market. Without the knee injury, Jacksonville likely would have made a concerted effort sign him to a long-term contract.

But the Jaguars nearly made it to the Super Bowl without him, beating Buffalo and Pittsburgh in the playoffs before squandering a 17-10 second-half lead against the Patriots in the conference championship game. The emergence of former undrafted rookie Keelan Cole, who led the team with 748 yards receiving in 2017, appears to be making Robinson expendable.

So instead of being a long-term option in Jacksonville, he could become a building block for another club even if it means not fully returning to pre-injury form in 2018.

With Garçon, Marquise Goodwin and Trent Taylor, the 49ers have a capable receiving corps signed for the coming season. But the future beyond 2018 is questionable for Garçon, who turns 33 in 2019 when there’s no guaranteed money left on his contract. San Francisco would be smart to find his eventual replacement as a No. 1 option before it’s absolutely pressing to avoid an awkward transitional phase.

Rookie receivers, after all, have struggled to adjust to the NFL early in their careers. The 2017 draft could prove as a cautionary tale for teams looking to make big investments in wideouts. Corey Davis, Mike Williams and John Ross all went in the top 10. They combined for 45 catches and 470 yards receiving and no touchdowns as rookies (Ross had zero receptions for the Bengals).

Dating back to 2012, only five of 25 wideouts drafted in Round 1 have played in the Pro Bowl: Odell Beckham, DeAndre Hopkins, Mike Evans, Amari Cooper and Cordarrelle Patterson, who made it as a returner. Of those five, only Beckham, Hopkins and Evans are sure-fire No. 1 receivers. Robinson was named to the 2015 Pro Bowl when he led the NFL with 14 touchdown grabs.

Projecting receivers at the next level has become increasingly difficult, largely because of simplified concepts in college systems. The draft would leave the 49ers a potentially daunting alternative if they don’t land Robinson as they look to solidify the long-term future of the position beyond Garçon.

Free agency next spring might not be much better. Evans and Beckham headline the 2019 class, but they are both assured to get the franchise tag if they don’t get new long-term deals with their current teams. If they did spring loose, they would cost significantly more than Robinson.

Otherwise, there don’t appear to be any options for a No. 1 wideout on the open market. Suffice to say, adding a potential top receiver like Robinson at such an early stage in his career offers the 49ers a unique opportunity they would be wise to take advantage of.

The financial landscape of the league allows teams to be aggressive thanks to the booming cap that’s increased 57.2 million since 2011. The 49ers have some $50 million in room to play with and Robinson could cost $10 to $13 million per year. That would leave plenty of room to find a starting cornerback and improve other positions of need.