You make personnel moves to try to improve your team as much as possible, not necessarily to match or scare your top rival, though that second part is probably pretty fun, too, I would guess.

So while I preach that NFL teams have to stick to their own plans in the spring movement period — which is now — and not try to hunt headlines and match any opponent’s splashy moves, and while I believe the 49ers and Seattle front offices are both sharp and not tempted to play the costly one-up-manship game…

There are probably some entertaining elements of hey-hated-rival-look-at-who-we-got going on the last few days between the 49ers and Seahawks, who happen to share a division and immediate title aspirations, and this will certainly continue through the free-agent phase and of course into the on-field skirmishes in the fall.

Which is a good thing, if done wisely, and by all measurement, the Seahawks and 49ers are doing some smart things right now and have done them for a few years.

That’s how they’ve both accrued so much talent, why they both are dangerous teams, and why both know that the other is the prime obstacle for future bountiful success.

(Pending St. Louis Rams improvements, and yes, they are getting better and better, too. What a division this is turning into. Sorry about that, Arizona.)

49ers-Seahawks is turning into New England vs. Indianapolis during the Peyton-Brady hey-day. Or Pittsburgh vs. Baltimore over the last decade-plus.

The best news about all that hot-rivalry history for the 49ers and Seahawks: Those four teams jousted with each other and went on to win 8 of the last 13 Super Bowls and either New England, Indy, Baltimore or Pittsburgh has represented the AFC in 12 of the last 13 Roman Numeral Games (and the last 10 in a row).

Yes, barring a rash of injuries to either franchise, I believe the 49ers (who are on a 1-in-a-row Super Bowl streak) and Seahawks could and maybe should end up making multiple Super Bowl runs over the next 5 to 7 years.

And I believe both franchises know it, love it, and — watching the other team beef up their depth charts — are a little afraid of it.

Again, that’s all tremendous stuff, and wait ’til they play each other in 2013, because it will only get better.

The latest: The 49ers are meeting with big-name/big-fall CB Nnamdi Asomugha today — as first reported by Matt Maiocco — and while Asomugha no longer counts as a massive splash, he does fit in with the general NFL West Supremacy theme.

It’s about acquiring the best talent as wisely as possible, and Asomugha, if he comes at a discount, is a tall corner who can do some things — only less well (so he will be paid much less) than in the recent past.

Earlier this week, Seattle acquired star receiver Percy Harvin; a few hours later, the 49ers acquired WR Anquan Boldin; I don’t think either thing was a reaction to the other, but it was very interesting, nevertheless.

At that point, I declared that these were now the two most talented teams in the NFL (with Baltimore losing a gusher of talent), and since then things have only gotten more interesting in the West.

Yesterday, the 49ers signed DT Glenn Dorsey to a very economical 2-year deal, reportedly worth about $7M.

And then Seattle signed DL Cliff Avril — maybe the most valued young lineman on the market — to a 2-year, $15M deal, which seems like an amazingly good price for such a talented player.

Today, I would imagine the 49ers are going to sign a DB or two — maybe Asomugha, probably a free safety in there somewhere, maybe even future Hall of Famer Ed Reed. (I thought LaRon Landry was a good fit for the 49ers, but he signed with Indianapolis.)

I’m not saying the teams are only doing these moves to counter the other — that’s essentially the opposite of what I’m saying. I think the two teams are going like mad to get better based on their own decisions… but that those decisions are largely AIMED at the other. That’s the difference and that’s the andrenaline-rush.

There will be more moves, more jousting, more fun… because the 49ers and Seahawks are both good, they’re both very aggressive, and they’re both so talented that they know any one move could be the one that puts them over the top… or else the move by their rival could be the one that kills them.

Let’s just run through some of the talent…

Seattle has great young QB Russell Wilson, great RB Marshawn Lynch, great CB Richard Sherman, Pro Bowl offensive linemen Russell Okung and Max Unger, Pro Bowl S Earl Thomas, talented DBs Kam Chancellor and Brandon Browner and now Harvin and Avril, among others.