That is a big reason why elite-level prospects are rarely traded at any time of the year, and why draft picks are often the cost of doing business at the trade deadline -- unless the return is a standout player who isn't a rental.
That being said, there are quality prospects traded at the deadline. A year ago it was Joe Colborne going from Boston to Toronto and Colton Teubert going from Los Angeles to Edmonton.
NHL.COM TRADE DEADLINE 2012
DETROIT RED WINGS
Top prospect: D Brendan Smith
Deep at: Forward
Smith would probably be in the NHL in about 25 other organizations, but the Red Wings are patient with their prospects and it is hard to argue with their success rate. He will likely be up full-time next season, and could help replace either Nicklas Lidstrom or Brad Stuart should they depart. Where Detroit GM Ken Holland is an advantageous spot is his collection of talented forward prospects.
The Wings are supplementing their stars with guys like Cory Emmerton, Darren Helm and Justin Abdelkader, while Gustav Nyquist, Jan Mursak and Joakim Andersson have made brief appearances. Detroit's top forward prospects are Nyquist, Tomas Tater and Calle Jarnkrok, while Tomas Jurco, Teemu Pulkkinen and Riley Sheahan could all be impact guys as well.
Holland has been a master of keeping his team among the NHL elite in the salary cap era, and he's probably at the zenith of his powers right now -- Detroit might be the best team in the League and the Wings might have the best top seven or eight prospects as well. He also has plenty of cap space available.
ST. LOUIS BLUES
Top prospect: F Vladimir Tarasenko
Deep at: Goaltender
In years past it was the Los Angeles Kings or Washington Capitals that possessed the best young goaltending depth in the NHL, but the Blues may have grabbed that distinction this season. St. Louis is set in net at the big-league level with Jaroslav Halak and Brian Elliott forming one of the best one-two punches this season. Better yet, both are just 26 years old and both are signed for two more seasons at a combined rate of $5.55 million.
The Blues also have a pair of goaltending prospects sharing the net with Peoria of the American Hockey League. Ben Bishop is 25 years old, was the MVP of the AHL all-star game and is probably the most NHL-ready goalie in that league. Jake Allen is 21, and has lost playing time as Bishop's star has risen.
St. Louis is still transitioning from rebuilder to contender, and GM Doug Armstrong probably doesn't want to give up any of his top prospects or high draft picks this weekend. Bishop is likely going to be a UFA this summer because of the time he has spent in the AHL without accumulating enough NHL action, so Armstrong could move Bishop for some help and allow Allen to receive more playing time while he is groomed to replace Halak or Elliott in two years.
NEW YORK RANGERS
Top prospect: F Chris Kreider
Deep at: Forward
Why have the Rangers been at the forefront of the discussions about a potential Rick Nash trade? Because the Rangers have built up a nice cache of young, impact talent to the point where dealing a couple or few quality young players and prospects won't "mortgage the future," as the saying goes.
New York has enviable depth on defense, from current NHL rearguards Ryan McDonagh and Michael Del Zotto to prospects Tim Erixon and Dylan McIlrath. Where the Rangers are really loaded is up front. One-third of their current forward contingent is 25 years old or younger (Brandon Dubinsky, Derek Stepan, Artem Anisimov and Carl Hagelin), and they have three top-50 type prospects in Kreider, J.T. Miller and Christian Thomas.
Obviously, a lot of these guys have been mentioned as potentially being part of a package sent to Columbus for Nash, but if Sather decides to do a smaller deal to help the Rangers try to win the Stanley Cup for the first time in 17 years, he has the resources to make it happen while still keeping an eye on the team's long-term future.
TRADE DEADLINE 2012
The NHL's 'Most Wanted' at trade deadlineBy Corey Masisak - NHL.com Staff Writer
NHL.com breaks down six of the most-wanted trade targets at the 2012 NHL Trade Deadline.
READ MORE ›
Top prospect: F Mikael Granlund
Deep at: Defense
In Granlund and Charlie Coyle, the Wild have two guys who could help ignite more offense in the Twin Cities in the near future. GM Chuck Fletcher dealt Brent Burns in the offseason (Coyle was part of the return) and might peddle Marek Zidlicky this weekend as well, but the reason he's able to move forward without those veterans is the deep crop of kids he has coming behind them on the blue line.
The Wild already have a quartet of young defensemen on the NHL roster (Jared Spurgeon, Marco Scandella, Justin Falk and Nate Prosser are all 25 years old or less). They also have 18-year-old Jonas Brodin, who looked great at the World Junior Championship and is primed to replace Granlund as the team's top prospect once he joins the Wild. There's also a couple of intriguing guys with the team's AHL affiliate in Houston in former first-round pick Tyler Cuma and undrafted free agent Chay Genoway.
Minnesota is on the fringe of the playoff race in the West, and Fletcher could deal from his depth on D if he wanted to help his club's offense.
Top prospect: C Mark McNeill
Deep at: Forward
When the Blackhawks had to say goodbye to several key players off the 2010 Cup-winning team, GM Stan Bowman made sure to collect a bunch of draft picks and prospects in the process. A year later, Bowman was able to retool the NHL roster -- but he still has a deep group of prospects at his disposal.
Chicago's superstars, Jonathan Toews and Patrick Kane, are still only 23 years old, but there are many young forwards to fill in behind them. Marcus Kruger has been a regular, while Jimmy Hayes and Andrew Shaw have seen extended looks with the Blackhawks. There are also guys like McNeill, Brandon Pirri, Brandon Saad and Jeremy Morin on the way.
Bowman has been pursuing a defenseman for some time. If that player ends up being a rental, he will probably only cost a draft pick or two, but Bowman has a ton of young forward depth to deal from if he wants a more long-term solution.
Top prospect: Jonathan Huberdeau
Deep at: Forward, Defense
GM Dale Tallon was one of the League's top sellers last season, and his reward is arguably the best farm system in hockey. While the Panthers have had surprising success this season and continue to battle for the Southeast Division title, there will be no such shock if they become Cup contenders in the next two or three seasons.
Tallon has an "untouchable" at every position in Huberdeau, defenseman Erik Gudbranson and goaltender Jacob Markstrom. Gudbranson is having a solid rookie year in Florida, and the Panthers' young defense corps (including Dmitry Kulikov and Keaton Ellerby) could also be joined full-time by Colby Robak and Alex Petrovic in the near future.
There's even more talent up front. Huberdeau will be a Calder Trophy favorite next preseason, while guys like Drew Shore, Nick Bjugstad, Quinton Howden and Vincent Trochek could also arrive in South Florida in coming seasons.
Tallon has said he won't make a deal to help the team make the playoffs for the first time since 2000 if it means giving away key assets for the future. If he wants to make a bigger deal that will help the team make the playoffs and compete for the Cup for several seasons, he has the assets to do that type of business.