Perhaps it's best when discussing 19-year-old Blues defenseman Alex Pietrangelo to understand the parameters. This is no longer about nine games.

"I know the one thing we're not concerned about this time is just nine games," Blues coach Andy Murray said. "He could be here for 30 games, 40 games ... or three or six games. Whatever it is, if we felt it was right to send him back, we'd do it.

"We're going to do the right thing. If we didn't know after nine games, we're not going to be stuck by that."

What the Blues do know is that Pietrangelo is different from last year at this time, when he held a tentative spot on the roster. Weakened by a bout with mononucleosis, hampered by a head and neck injury, trying to parlay just 18 years and zero experience into an NHL job, Pietrangelo stayed eight games before the Blues sent him back to the Ontario Hockey League's Niagara Icedogs.

If the club keeps Pietrangelo beyond nine games, the clock on his NHL career and the organization's holding rights begin to click. Last year, under the circumstances, it made all the sense in the world not to spend a year of contractual binding on the promising young defenseman, who clearly was not ready.

This year is different, for the club and the player. "I mean really, when you think about where I was last year, with the mono and the time I had in training camp ... it's come a long way," Pietrangelo said.

A native of King City, Ontario, Pietrangelo spent most of his summer in St. Louis, fitness training, skating and getting to know teammates. He stood out during the Blues' preseason camp as one of the most improved players. Murray has no frame of reference for Pietrangelo, whom he did not see as a junior.

The Blues' mentor has no preconceived notions one way or the other. But he was able to contrast the player he saw in the recently completed training sessions to the one he saw in 2008, and they were worlds apart. "It was not even close, " Murray said, after putting his team through a rigorous practice Monday. "He is much stronger on his skates. Last year he was a bit ... overmatched is a good word."

As the Blues opened the season in Sweden with consecutive games against Stanley Cup finalist Detroit, Pietrangelo was a healthy scratch. He was in coat and tie for the home opener last Thursday as well, a 4-2 loss to Atlanta. But with Barret Jackman on injured reserve with a sprained ankle, Pietrangelo cracked the lineup for the first time this season Saturday, skating slightly more than 13 minutes in a 2-1 loss to Los Angeles.

For the 6-foot-3 Pietrangelo, it had been a long time between shifts and he was a bit tentative at the outset, but he looked more comfortable in the latter stages. Keep in mind, you don't often sit in the press box for two weeks as a junior.

"It does take a few shifts to get back into the swing of things maybe," Pietrangelo said. "It was kind of a new thing for me, but that's part of being a pro. You have to be ready all the time, whether you're playing the next night or in three weeks."

At the same time, it's difficult when you are a new pro defenseman to make your presence felt, to impact a game the way you did as an amateur. Blues Hall of Fame defenseman Al MacInnis will tell you it takes 200 NHL games or so before a defenseman feels comfortable in his skin. The challenge for Pietrangelo is not so much to turn heads during games, but to make his statements in practice.

"It's tough to be good in games as a young player, if you're not good in practice," Murray said, "If you're a Keith Tkachuk or an Allen Iverson, you still want them to be good in practice, but the differential isn't the same. A guy like Keith may have a bad practice — and he hasn't had many this year — but he knows how he has to play in games.

"But a young player doesn't have that experience. He has to be good in practice, has to be good in practice."

Monday was a good test. Murray ran the Blues through numerous versions of one-on-one drills. The skating was relentless, the tenacity high and the physical battles fierce. For Pietrangelo, wrestling for possession with the stout-figured Tkachuk, or the 6-5, 230-pound Brad Winchester, is considerably different from going into the corners with other 17-year-olds.

There is room for Pietrangelo if he is ready. One of the Blues' shortcomings in an otherwise uplifting 2008-09 season was a lack of offensive skill on the blue line. That area promises to be better with the return of Erik Johnson, but the defensive group overall still leans heavily on the steady, stay-at-home side.

Through four games, the only goal the defense has belongs to Roman Polak, who, by the way, doubled his career total with that marker. Johnson has three of the seven assists spread among the seven defensemen. Pietrangelo had eight goals and 21 assists in 36 games for Niagara last season, 13 goals and 40 assists the season before.

He has passing and shooting abilities the Blues could certainly use, on the power play if nowhere else. But Murray emphasized he would not keep an up-and-comer as a one-trick specialist. The organization made Pietrangelo a No. 1 pick, and fourth overall in the 2008 draft, with expectations he can be more.

"We wouldn't keep him just for that reason," Murray said. "You may keep an older player as a specialist, but you wouldn't keep a young player as a specialist, simply because you're hoping that player will round his game off and become a better (overall) player. With a veteran, his playing profile has been defined. Alex's profile has not; he still has a big learning curve."

"It's not my decision, obviously, all I can do is play," Pietrangelo said. "But I do think it is more beneficial. Practicing here and playing here is going a long way (in his development) as opposed to going back down there and playing.

"Not that going down wouldn't be challenging, but here everyone is just as smart and just as strong. So you have to make sure you know that hard work goes a long way. There's a lot of things you can't get away with here that you can get away with there. Playing with better players makes you a better player."