As fantasy owners, we tend to overreact.

One big game. One bad one. One walk-off celebration that results in a broken leg.

When Buster Posey -- the Giants' catcher of the future and one of baseball's top prospects -- was 3-for-4 with three RBI in his 2010 debut on May 29 against Arizona, we all took notice.

And many of us scrambled to get to our league's waiver wire.

Posey, who is eligible at catcher in most leagues, even though he's playing first base for the Giants this season, already is owned in 49.2 percent of the leagues on ESPN.com and 47 percent on Yahoo. Because catcher is such a goofy position this season -- the home-run leaders at the position are Rod Barajas, John Buck, Chris Snyder, Mike Napoli and Miguel Olivo -- the guess here is Posey is starting in most of the leagues in which he's been acquired.

If you're one of the instant believers, don't get too excited by the fast start of the No. 5 overall pick in the 2008 draft.

Posey entered this season with all of 17 major-league at-bats, and it wasn't long ago we expected instant offense from Orioles catcher Matt Wieters. In Year 2, Wieters is batting .246 with four homers (half of the total for Buck, Snyder, Napoli and Olivo), 12 runs and 16 RBI.

Posey has hit everywhere he's been. He was tearing up Triple-A this season -- a .349 average, six homers, 32 RBI and a .994 OPS in 47 games.

In 2008 and '09 in the minors, he batted .327 and had 94 runs, 19 homers, 86 RBI, six steals, 36 doubles and a .959 OPS in 459 at-bats. Then there was spring training with San Francisco this season, when Posey batted .315 with a homer and nine RBI in 54 at-bats.

Will he be a stud? Probably. But the same goes for Wieters, who turned 24 on May 21.

The latter is about 10 months older than Posey and played less than two seasons in the minor leagues. In a combined 578 minor-league at-bats in 2008 and '09, Wieters batted .343 with 32 homers, 121 RBI and a ridiculous 1.014 OPS.

On the day Posey made his triumphant 2010 debut, Giants veteran Aubrey Huff jokingly referred to him as "Jesus Christ" because of the hype.

Posey then had three hits and RBI No. 4 in his second game of the season. Counting Tuesday night, he was 1-for-7 in his next two contests.

Posey eventually should be a fantasy player to covet. If you can play him at catcher, he has some value now.

At this point, however, we'd settle for the 2010 Posey being compared to Rod Barajas at the plate.

Since the Rangers rank in the top eight among among major-league offenses in home runs (second), total bases (second), slugging percentage (second), RBI (fifth) and runs scored (eighth), you would think replacing an injured Josh Hamilton might be as simple as glancing at Texas' depth chart.

You would be wrong (but if you want to waste your time, as I did, here it is).

Hamilton, a second-round pick in many leagues after a monstrous 2008 (.304, 32 homers, 130 RBI, .901 OPS), will miss four to six weeks with a partially torn abdominal muscle. He's played in only 35 games and has been one of fantasy's bigger disappointments with a .240 average, six homers and 24 RBI.

His extended absence will mean more time for David Murphy and Andruw Jones, but not enough to warrant fantasy consideration.

With Hamilton out, Murphy has been starting against right-handers. He batted .275 with 15 homers and 74 RBI as a rookie last season, but he hasn't lived up to that billing in 2009 (.259, two homers, 12 RBI). He has improved this month (.368 and two RBI), but you'd have to really need outfield help to consider him.

And you'd have to be playing in a 16-team AL-only league to consider Jones, who has decent numbers (.269, five homers, 15 RBI in 92 at-bats), but usually only starts against lefties and has only seven at-bats in June.

The playing time of the Rangers' starting center fielder (Marlon Byrd) and right fielder (Nelson Cruz) shouldn't be affected much by Hamilton being on the DL. The impressive Cruz (.291, 17 homers, 42 RBI, nine steals) is a fantasy starter, and Byrd (.299, four homers, 26 RBI, two steals) is useful strictly in AL-only leagues. Even then, he's only going to help you in batting average and possibly RBI.

If you own Hamilton and need outfield depth, the four who follow are all owned in fewer than 50 percent of the leagues on ESPN.com (ranked in order of projected effectiveness the rest of the season): 1. Jose Guillen, Royals (.255, six homers, 25 RBI, 9.5 percent ownership); 2. Jason Kubel, Twins (.304, seven homers, 31 RBI, 45.1 percent); 3. Melky Cabrera, Yankees (.304, six homers, 23 RBI, four steals, 25.9 percent); 4. Aaron Rowand, Giants (.309, six homers, 27 RBI, four steals, 22.5 percent).

Looming ...

-- John Smoltz will make his fifth (and last) minor-league rehabilitation start for the Red Sox on Thursday. Smoltz, who is coming back from 2008 shoulder surgery, is 42 and hasn't pitched in the big leagues in more than a year.

Then there's this: Smoltz has the following career numbers: 210 wins, a 3.26 ERA and 3,011 strikeouts in 3,395 innings. He was also effective before the injury ended his 2008 season in Atlanta (3-2, 2.57 ERA, 36 strikeouts in 28 innings).

Clearly, the latter paragraph is beating out the concerns from the prior graph. When Smoltz is ready to join Boston's starting rotation (warning: scoop to follow), someone has to go, and that pitcher could be Brad Penny, who's won five games.

If Smoltz is available and you play in a 10- or 12-team league, he's worth a look. Don't expect huge results -- WEEI reported Monday that the Red Sox might occasionally skip his starts to keep him healthy -- but if he gets the call twice in a week, he should be an effective play.

Penny, who is owned in 12.2 percent of ESPN leagues, has too high of an ERA (5.85) and too few strikeouts (39 in 60 innings) to be a regular fantasy starter. He is an asset, however, and a return to the National League likely would boost the fantasy value of the 31-year-old who won 16 games with the Dodgers in both 2006 and '07.

If Boston doesn't trade Penny, there's a chance Tim Wakefield (7-3, 4.50 ERA) could be moved to the bullpen, which would wreck his fantasy status faster than you can say "Spencer Pratt."

Penny or Wakefield would have to be the odd man out when Smoltz returns, since Josh Beckett and Jon Lester certainly aren't going anywhere, and Daisuke Matsuzaka's hefty contract does for him what his results do not (1-4, 7.33 ERA).

-- Brandon Webb, who has started all of one game since he was selected as one of the top two or three pitchers in almost every draft, is targeting Friday for his first throwing session on the mound. Webb expects to return from a shoulder injury before the All-Star break, which would mean you wouldn't get Arizona's ace back in your lineup until about Week 15 (July 6-12).

Webb's ownership percentage in ESPN leagues is 98.8, meaning some guys and gals out there are getting sick of holding his roster spot. If someone in your league is so foolish, take the gift and hope you get a pitcher who at least slightly resembles the player who won a combined 40 games and struck out 377 batters the previous two seasons.

Not so fast

Matt Wieters' big-league debut was hyped as the catcher's version of a young Alex Rodriguez or Ken Griffey Jr. with the Mariners.

Thus far, the Oriole has more closely resembled Kelly Shoppach. Wieters is 4-for-28 with zero RBI in eight games.

That will change. Wieters, after all, became one of MLB's top prospects because he tore up the minor leagues (.343, 32 homers, 121 RBI, 67 extra-base hits and a 1.014 OPS in 578 at-bats), and he eventually will hit in the majors.

Already, he's owned in 84.2 percent of the ESPN leagues -- a surprisingly high number when you consider Jim Thome is owned in only 81.1 and Todd Helton 74.6 -- which means he's probably starting in most leagues.

I wouldn't make that move in mixed leagues. Until Wieters has a good week, I'd play someone else -- unless your alternative is Shoppach.

Tomorrow, we'll be back with a Pick Three for the week, and Saturday we'll break down what's sure to be a very difficult decision in football drafts late this summer: Who should be drafted No. 2, after Adrian Peterson? That story will be published in print editions and on the N-H's online sports section.

Until then, good luck and remember it's OK to hope Joe Buck's new HBO show fails.