And we're not talking here about things such as money, cars, women and fame - things that have been known to tempt other talented football prospects to declare for the NFL draft after their junior season.
No, Rachal had a much better reason than those. A real reason.
"I came out early because of my mother," Rachal said. "She had a tumor the size of a six-month-old in her stomach and has no insurance. And my dad's dealing with injuries - two hernias got taken out of his stomach - and he has no insurance. It was very hard because I did want to return to USC. But in my situation, I had to do what is best for my family at this time."
Had he remained in college, several draft analysts have said Rachal would be a sure first-rounder in the 2009 NFL draft, perhaps one of the first offensive linemen selected. As it is, he didn't last long in this year's draft before the 49ers selected him in the second round with the No. 39 overall selection.
Rachal soon will have the financial means to help his mother Veronica Pickett and father Charles Rachal, who currently are relying on Medicare to fund their medical treatments.
"But without good insurance, you can't get the treatment you really need," Chilo said.
The Rachal family already has suffered through enough heartache and heartbreak. Two of Rachal's older brothers - they had the same father but different mother than Chilo - were gunned down in violence on the mean streets of Los Angeles.
One brother was 23 when he died. The other was 18. Chilo never got to know one of them, who was shot dead shortly after Chilo was born. The other was killed when Chilo was eight.
"You just try to keep positive, motivated," Rachal said of tragedy his family has faced. "My brothers have passed. They were out in the streets. I don't know the full details because I was so young when they were killed. I guess they were out doing something they had no business doing. I had a rough upbringing, but I was always the one in the family that made the right decisions."
Staying focused and determined to make something of himself, Rachal was a highly-decorated prep All-American as he entered his senior season at Dominguez High School in Compton.
But his season of big dreams and expectations ended abruptly when he suffered a knee injury that limited him to just four games. Still, that didn't stop him from earning a scholarship to USC, where he redshirted as a true freshman.
Two years later, Rachal was earning sophomore All-American honors for the Trojans, gaining a reputation as a dominant blocker for one of the nation's best offenses. He was even better last season as a junior, earning recognition on several All-American teams and earning first-team All-Pac 10 honors.
Rachal did not allow a single sack or quarterback pressure the entire season, developing rapidly in a pro-style system under the direction of head coach Pete Carroll, a former 49ers defensive coordinator. He was credited with 77 knockdown blocks, nine of which paved the way to USC touchdowns.
Rachal's talent should fit right in with the 49ers, who need quality depth - not to mention future starters - along their offensive line after losing guards Justin Smiley and Larry Allen and tackle Kwame Harris during the offseason.
Rachal, in fact, could move into a starting role as a rookie, replacing the injured David Baas - who won't return until late in training camp this summer - or Allen, the sure-thing Hall of Famer who no longer is with the 49ers and appears headed toward retirement after 14 distinguished NFL seasons.
Rachal has drawn some comparisons to Allen, and that certainly is OK with the 22-year-old prospect.
"My favorite player is Larry Allen," Rachal said. "That's the guy I resemble, the guy I compare myself to. Those are some really big shoes to fill. It feels pretty good to have the opportunity to work behind somebody who he is."
Rachal worked in with the first unit on offense immediately over the weekend during the 49ers' spring minicamp, sharing time at right guard with Tony Wragge, who is listed as the tentative starter while Baas recovers. He looked good and appeared to pick things up quickly in his first practices as a professional.
It appears only a matter of time before Rachal takes over a starting position and cements himself there for many years to come. There is even talk that he has the versatility to move out to tackle, a position he played in high school.
"He'll compete for a starting position," 49ers coach Mike Nolan said. "He's a tough guy with a lot of talent. We're excited about him. I believe he'll make an impact this year."
Just as important to Rachal is making an impact for his family. And coming to the 49ers will allow him to remain close to his mother and father and two living siblings, who are only a five-hour drive away from watching him play his home games as a professional.
His mother's tumor is not malignant, and she recently has received injections to shrink the growth. If the shots don't help, doctors may need to operate to remove it.
But Rachal soon will be able to help his mother get the best care possible. And now that he's a 49er, he'll never be far away.
"I'm very happy about that," Rachal said. "I kind of stay close to home. I knew I had to make the decision that was best for my mom. I love my mother and I'm going to do the best thing I can to put her in a better situation. She's my motivation every day I wake up."
Family comes first for Chilo Rachal
Niners Digest Top Stories
Week 2: Fantasy Football Deep SleepersFantasy Football Expert Jack Delaney reveals some under-the-radar players that could help you gain an edge in your Week 2 matchup.
2016 Expert Sleepers, Busts & BreakoutsThe best high-stakes Fantasy Football Experts and world's highest-ranked fantasy players have contributed to what we call Preseason Pro. A collection of hand-picked fantasy…
Top 10 NFL Celebration FailsRevisiting some of the worst celebration fails in NFL history.
Scout NFL Network08/24/2016
10 greatest one-handed catches in NFL historyCheck out the most jaw-dropping, awe-inspiring one-handed catches of all-time in the NFL. Find out who comes in after Odell Beckham's catch against the Dallas Cowboys.