Injuries happen. Underperformance takes place. Projections can be off.

You see it every year in college basketball. Supposedly one-and-done, lock-lottery picks fail to reach expectations for a variety of reasons.

But that’s why the word “potential” is so often tossed around. It is also why the new G-League model, one that is paying elite recruits up to $500,000 to join a “select team” of top prospects and veteran G-League players rather than attend college, is such a risk for these players.

In theory, it is a great idea, giving young men who don’t want to attend college or travel overseas to play professionally another avenue to make money right out of high school. Already, two five-star prospects — Jalen Green and Isaiah Todd — have signed with the G-League, and the expectation is three more will follow. The guaranteed one-year contracts include an academic scholarship to Arizona State that is good until five years after a player is done with his career.

“I got a call and then it was kind of like irrefusable,” Todd said Tuesday on NBA-TV. “It just sounded perfect, and it sounded like a no-brainer.”

Left unanswered is what happens if not everything goes according to plan. What if a player destroys his knee? What if he struggles to the extent he could go undrafted? What if he just isn’t ready to go to the next level? Then what?

In college, there is the option of staying in school. Or transferring. There are fallback choices. The G-League doesn’t offer the same opportunities. The players have no choice but to enter the draft. The G-League select team only offers one-year contracts.

“That’s what we call short money,” an NBA scout said, speaking on condition of anonymity.

The 6-foot-5 Green is a consensus top-three prospect. He’s not taking nearly the risk of the rail-thin 6-10 Todd, who is raw by comparison and ranked 14th in his class by 247Sports.com.

Green most likely will be fine. He will get drafted early on pedigree and promise. The same might not be able to be said about Todd, who passed up a scholarship to Michigan to head to the G-League. You can find plenty of players ranked from 10-20 every year who aren’t ready for the pros after one year, who need more seasoning and development. Some of those players could wind up in the G-League now.

A college coach told The Post he believes the NBA is doing this to eliminate question marks its teams have about elite prospects while paying them a far lower salary than a first-round pick would garner. This would enable them to get to know the player far better than if he were in college, to know whether he has poor work habits or a me-first attitude, traits that can sometimes be shielded.

“This is a way for the NBA to thoroughly vet kids on the cheap,” the coach said. “It’s a paid tryout.”

The NBA source dismissed this as motivation. It’s their job to know everything about the kids their teams end up drafting.

“All they’ve done is create more opportunities for us to watch them practice,” he said.

Asked about the NBA getting a closer look at these prospects over the course of one year, G-League president Shareef Abdur-Rahim told The Post: “It will help that player to start preparing for the NBA game and NBA style of play, which is different.”

One college coach said there is low risk because the types of players the G-League is going after are prospects the NBA believes have a legit opportunity to play in the league. When told it is a one-year contract, that coach did acknowledge there is risk.

“But the player is screwed [but at least has] money,” the coach said.

Another coach said he sees this as the NBA challenging the NCAA to make much-needed changes, that it is flexing its muscles at a time the NCAA has continued to drag its feet when it comes to compensating student-athletes, making the G-League path that much more enticing.

All are valid arguments, and the New York Times reported on Wednesday that this idea could even expand — to the point where the G-League creates a division of select teams, though it has only been discussed and would depend on how much interest and success the plan has initially with just one team.

In the end, however, it is the kids who are rolling the dice, hoping their promise and potential leads to a profitable pro career. They are the ones taking the risk. They are the ones who won’t get a mulligan if the G-League select team backfires, if they underperform or get hurt.

These are 18-year-olds making difficult decisions, choices they could end up regretting years later, leaving themselves no wiggle room.

“Unfortunately,” one of the college coaches said, “these kids don’t think there will be a fallback option needed.”