There are no LeBron James-magnitude free agents in the NFL, although if James wanted to play football, he probably would be the exception.
If any mortal could chase down Colin Kaepernick in full gallop, I would put my money on LBJ.
Otherwise, as we wait for the free-agent-signing window to open Tuesday, I have two words for owners, general managers and eager fans everywhere:
Except in the rarest of cases, no single expensive player can guarantee blessed fortunes for an NFL franchise the way LeBron's arrival in Miami signaled prolonged glad tidings for the Heat.
NFL reality: Fans love any and all big-name acquisitions, yet there is no such thing as a pricey quick fix, and if you sign multiple big free agents, you're more likely to actually get worse.
Just ask the Philadelphia Eagles, who threw their checkbook at cornerback Nnamdi Asomugha and others in a 2011 splurge and still are digging out from that error.
Or the Buffalo Bills, who handed $50 million in guaranteed cash to defensive end Mario Williams in a six-year deal last offseason and still were terrible on defense in 2012.
Or the Seattle Seahawks, who gave quarterback Matt Flynn $10 million guaranteed for three years and then wisely made him the backup to third-round pick Russell Wilson.
Or the Raiders with their spend-in-the-spring-lose-in-the-fall outcome almost every recent year until the 2011 regime change.
You need a strong personnel system to win big in the NFL -- teams with strong systems almost always produce their own stars and don't need to import them from other teams.
This is not to say that there aren't many very talented free agents available this offseason, as there are every offseason.
But how many free agents have been true difference-makers and changed a good team into a great one?
Of course, Reggie White and Deion Sanders altered NFL history in the early 1990s when they changed teams ... but that was almost two decades ago, when free agency was young.
More recently, the biggest impact has come almost solely from free-agent quarterbacks, and each with unique back stories.
Rich Gannon was hardly a marquee free agent, but then he revitalized his career and the Raiders under Jon Gruden.
Peyton Manning (from Indianapolis to Denver) and Drew Brees (San Diego to New Orleans) were special cases -- franchise quarterbacks who were on teams that had already picked their replacements.
OK, on to the current local landscape ...
The 49ers could use a wide receiver or two, a free safety (if they can't re-sign Dashon Goldson) and a few pass rushers behind Aldon Smith and Justin Smith.
Side note: Justin Smith was one of the great free-agent signings in recent NFL history when he jumped from Cincinnati to the 49ers in 2008.
The Raiders could use help everywhere, especially on the defensive line, at linebacker and at cornerback.
But the smartest teams avoid the big markups in the early rush and take their time sifting through the remainder bin.
That is how the 49ers landed Carlos Rogers and Donte Whitner in 2011 (when their fans were screaming for them to spend whatever it took to get Asomugha).
The 49ers already have made their largest offseason deal by agreeing to trade Alex Smith to Kansas City for a second-round pick this year and a premium conditional pick in 2014, and the draft always will be G.M. Trent Baalke's sweet spot.
So I don't expect the 49ers to chase any of the spring headliners, whether in a trade for cornerback Darrelle Revis or on the open market, bidding for wide receivers Mike Wallace or Wes Welker.
Under Baalke, the 49ers have preferred the low-profile route, scooping up solid players for value salaries (Whitner, Jonathan Goodwin) or taking in big-name players at bottom-rung prices (Randy Moss).
Some value possibilities: slot receiver Danny Amendola, kick returner/receiver Josh Cribbs, defensive end John Abraham and kicker Phil Dawson.
The Raiders have to do it similarly low key, at least until they get their salary-cap situation back into shape.
The Raiders could get a big jump on the cap savings if they release quarterback Carson Palmer outright, but I doubt things will go that far.
The Raiders need a credible starting quarterback to work in front of Terrelle Pryor, and Palmer needs a comfortable home and a team that wants him. The two sides should be able to find a compromise.
Last year, Raiders G.M. Reggie McKenzie signed a few midlevel guys -- Mike Brisiel, Philip Wheeler and others--and didn't get much from them or anybody else.
I can't confidently list realistic Raiders possibilities this year, because I couldn't have named any of the players they ended up with last year.
But talented Tennessee Titans tight end Jared Cook could be an interesting addition to any offense, including the Raiders, who seem to be ready to lose starter Brandon Myers.
Beyond that, I'm sure a few teams will spend lavishly in a few days and revel in the praise; and the 49ers, the Raiders, the Ravens, the Giants and several others probably will not, and probably will get some criticism.
The sting of that goes away, however, by January, if you're in the playoffs and the big spenders are spent.