Success in sports is all about confidence. 

Avery Bradley has it right now and Jose Iglesias – despite his home run Wednesday in a minor league game in Florida – doesn’t.

It’s why Bradley has been able fill the void left by the ankle injury to Ray Allen and it’s why Iglesias couldn’t take advantage of a spring training opportunity to win the starting shortstop job for the Red Sox.

They are two fascinating studies of what the future holds for two franchises in undeniable transition.

The Celtics were forced to look to the second-year player due to Allen’s turning his left ankle on March 12 in Los Angeles and an NBA roster limited to 15 spaces.

The Red Sox have the luxury of a 40-man roster and veteran names like Mike Aviles and Nick Punto to hold Iglesias’ spot warm until he proves he can consistently hit or layoff breaking and off-speed pitches.

Bradley just turned 21 last November and is in his second NBA season. If there had been no lockout, there’s a chance he might have started the season in the D-League with the Maine Red Claws, where he played big minutes last season.

But the lockout placed a priority on young healthy legs, and with Paul Pierce nursing a sore heel that forced him to miss two weeks of camp in December, Bradley stepped in and filled the void off the bench while Mickael Pietrus and Brandon Bass were starting more and more games.

He looked the part of a young player still trying to find his way in the NBA. He broke double digits in scoring just once in the first month of the season. But then he started eight straight games as Rajon Rondo nursed a wrist injury.

The team didn’t fall apart. They won six of the eight games from late January into early February. That was a foundation – a base – for Bradley to build upon. But then came his breakout game against the Wizards last Sunday. He scored 15 points in the first quarter, outscoring Washington by two. It wasn’t Bradley’s fault they gave him five layups. He took advantage, on his way to a career-high 23 points and a Celtics win.

Now, Allen and Pietrus are out and the Celtics are in dire need of contributions from guards not named Allen or Rondo. 

Bradley has picked a pretty good time to go on a roll. He’s started the last four Celtics games going into Friday’s contest in Minnesota, allowing Doc Rivers to give Allen time to get his ankle right for the playoffs.

“Just his confidence, you know that’s all it’s pretty much been with him,” Pierce said after Bradley’s solid 43-minute effort in Wednesday’s win over Utah. “You know getting the experience, getting the confidence. You know his ability he shows it when we are able to practice, like I said before it’s about getting that in-game experience and he’s gaining that confidence, and he’s comfortable out there, he’s understanding what Doc wants from him and he’s looking good out there.”

Midway through the fourth, it was Bradley – not the resting Rondo - leading the cast of Keyon Dooling, Greg Steimsma, Kevin Garnett and Ryan Hollins. Forget their charge to the top of the Atlantic, raise your hand if you thought that was possible for a contending Celtics team.

“It means a lot,” Bradley said. “Earlier in the season I had the chance to gain confidence, and now I’m even more confident. And every game I go in and like I said, I know my defense can always beat the point if I play hard. So I play harder defense, and I let everything else work itself out. I get points off of cuts, I just go in there and play hard for my team.

“You know I feel a lot more confident because I know my teams and Doc really are behind me. I know what they expect, I’m not out there lost, I’m a lot more confident, I don’t second guess anything I just go out there and play my game.”

His coach didn’t argue.

“Obviously we can tell he’s far more comfortable at that position and unfortunately for him, in a lot of ways, we’ve had to play him at the other position, but I think it gives him confidence,” Doc Rivers said of Bradley’s play-making ability at shooting guard. “One of the things I’ve said consistently all year is that he can shoot the ball and he was making me a liar for most of the year. It was great to see him go in. I thought there was a point it was clearly confidence because you see him in practice and he makes them, then he gets in the game and he just needed one to fall and that’s the other thing we kept saying, so that was good.”

Compare that, if you will for a moment, to these words this week from Bobby Valentine on 22-year-old Jose Iglesias after the shortstop was sent to Triple-A Pawtucket to start the season.

"He needs to work a little more on the consistency of his swing and play," said Valentine. "He's been working on things, and about two weeks ago, he had a mechanic that looked like it was real functional. I think an 0-for-3 took him out of it. That's one of the things he has to develop, a confidence in his program."

Iglesias started off hot in spring training at the plate, going 3-for-10 in his first four games. Then he pulled his groin and had two hits in the two weeks leading up to Wednesday’s decision to pull the plug.

"I don't stop believing in a player until I see him stop believing in himself," Valentine said. "He came into the dugout [after an at-bat] with a look of wondering that I don't like to see. This is not the time to be searching. You have to go into the season not searching."

Iglesias’ response: "At the end of the day, I can't control that. Get better -- that's what I can control, and that's what I will."

All about confidence.

Bradley has so much right now that he’s playing not one, but two positions in the NBA.

Iglesias - partly because of an unlucky injury - is back to Pawtucket to prove to the Red Sox he belongs back with the big league team soon.

Barring trades, both players have bright futures with their respective organizations. Bradley just has a big head start.

To the Trags Bag for your take on the futures of the two young stars. 

Will Bradley slip into the No. 2 guard spot next to Rondo next season if Ray Allen is out the door?

@JdotD @Trags No, AB too small to guard SGs. He makes for a good backup though, as long as his PG ability/vision continues to improve.

@LucidSportsFan @Trags definitely maybe.

@Joe_Bettencourt @Trags Bradley a good combo guard off the bench, sub for and play with Rondo, prefer more size and scoring for a starting 2 guard

The thinking among NBA executives right now is that Bradley is nothing more than a stopgap measure at the shooting guard spot because of his size (6-feet-2). He can certainly defend in transition but is very vulnerable on the low post, as was seen on Wednesday Gordon Hayward posted him up and got to the basket often. He is still learning the point and obviously, still need to work on his jumper. But that didn’t stop Rondo from developing.

Who will have the bigger future ahead of them, Bradley or Iglesias? 

@Dunkfaced @Trags Iglesias due to the fact that Boston seems set on guards with Rondo + possibility of Rivers.

@0_LayDX @Trags #TragsBag Avery Bradley, already has the defense (like Jose) but has shown he can play offense and be very consistent

Iglesias has two huge things going for him besides his age. There is opportunity and he has loads of skill, well-developed defensively and still raw offensively. The stage is set for Iglesias to develop into the shortstop of this decade for the Red Sox. He will not be Nomar Garciaparra or Alex Rodriguez but watch him enough and you can see why there are those in the sport who have compared his range to Derek Jeter when the Yankees shortstop was coming up. Jeter turned into a hall of famer because he could hit, even developing some power. Mark my words, Iglesias will be up in the majors when he learns to hit the breaking ball or lay off it. Anxious young hitters jump at pitches in the batter’s box. All batters, great and not-so great, guess from time to time – they just usually do so from their back foot, not before they’ve already committed.

So, was it the right call to have Iglesias start 2012 in Pawtucket? 

@s_thorn @Trags Beyond the right call, it's the easy call. He was obviously not ready offensively. Very easy to see. Batted under .200 this spring. Not only that, he never showed he was ready offensively in Pawtucket last yr. Not sure why ppl would think he can hit at ML level now

@JJensenRF @Trags As we watch catchable singles trickle through the sieve on the left side of the infield, we'll wish that we had abetter glove there.

@IrishRedSox77 @Trags I think it's a good move so he can work on fielding w/PawSox but depending on how Aviles does, it's good to know Iggy is right there.

@mlodi3430 @Trags Yes, allow him to get more confident at the plate. He is still young and Aviles has great potential as well (.300 hitter) #TragsBag

Let’s face it. This team needs to win now and they’ve determined that they need to do offensively. That’s what this means. They can’t afford to have Iglesias carrying his bat and his slumping shoulders back to the dugout in April when the team is trying to avoid the 0-6 and 2-9 start of 2011. There was no way in the world Iglesias could bat leadoff but his replacement Mike Aviles can. That factor can’t be overlooked, either. Aviles gives the Red Sox a better chance to win early.