Let's look at the numbers of three defensemen who played last season. All three were eligible to be unrestricted free agents. One signed a deal before reaching free agency, the two others became free agents and signed with other teams. All numbers courtesy of hockey-reference.com:
Whatever the case, we don't see that much difference between these three players, do we? Player A only got into about half the games (he was also injured for some time), but still played infrequently when he did get in. Players B and C didn't get into all the games either, but they got more ice time. In all, wouldn't we expect these players to be paid about the same? And no, I'm not pulling any tricks here - their previous years really aren't that much different from one another, and it's not like one guy is 38 years old - all are within or close to an NHL prime.
It may be surprising to learn that Player A received a 2 year contract worth $1.225M per season, Player B received a 1 year deal at $1M, and Player C received a two-way contract worth $650K. What gives? How does Andrew Alberts (aka Player A) merit a 2 year contract, at more than double the league minimum, by playing 15 minutes a game? It's somewhat simple - Alberts is being paid that way because he's accepting that he will likely be the Canucks' 7th defenseman next year. It's possible that he could've left Vancouver and gotten a promise to play in the top 6 somewhere, but he would've given up money to do so. Alberts has played nearly 400 games for 4 different teams; you know what you are getting when you sign him.
Player B, Jim Vandermeer, didn't know he was going to be the 7th defenseman when he signed with the Sharks, but with the addition of Colin White, that's now likely. Vandermeer has over 400 games of NHL experience with 4 organizations, so he's somewhat of a known quantity at this point. He wasn't able to get more than 18 minutes a game for the worst team in the NHL.
Player C is Jack Hillen, a player who got nearly 21 minutes a game for a bad Islanders team in 2010. Hillen was mysteriously non-tendered by the Islanders this part off-season - are the Islanders really in a position where they can just give up players? Apparently so, and it took until August for Hillen to sign somewhere. However, Hillen only has 175 NHL games under his belt, and he's only played for the Islanders. Even though Vandermeer and Alberts are likely worse players than Hillen, it appears that few teams were willing to gamble that Hillen can fill a top six role. One can imagine the rhetorical question appearing in a general manager's mind: 'If the Islanders don't want him, how good could he be?' And perhaps Hillen himself rejected offers from places with 6 defensemen likely to be on the depth chart above him, because he doesn't have a career history to fall back on - one poor season and he might be looking at offers from the KHL and Swiss leagues as his only options.
I fully expect Jack Hillen to outperform both Alberts and Vandermeer this season. The Predators may not have as much money as the Canucks and Sharks, but they know a good investment when they see it.