TCU and West Virginia don't "officially" join the Big 12 until July 1.

But nothing happens in July. In March, we have spring football, and in every meaningful sense, the Horned Frogs and Mountaineers have become the first teams to join the Big 12 since its creation back in 1994.

Big 12 teams are showing up on both programs' new film for 2012. Recruiting efforts are shifting.

It's a new world in the Big 12. If you lost track, it still has 10 teams.

Since June 2010, though, it has lost four teams (Nebraska, Colorado, Texas A&M, Missouri) before gaining two more back in October.

The Big East let TCU, which had promised to join the league in 2012, go without incident. Months of legal wrangling and a hard-to-swallow $20 million price tag for leaving were needed for the Mountaineers to make it official.

The Big 12 lost a lot when storied Nebraska left for the Big Ten. It lost nowhere near as much when Colorado left for the Pac-12.

Two big programs with lots of eyes, in Mizzou and Texas A&M, are gone. There's no getting around it: They'll be missed in some ways. You can't replace a century of rivalries without a century of new rivalries. And even then, it's difficult.

Missouri-Kansas? Texas A&M-Texas? You can't replace that, no matter how hard you try. Both rivalries -- annual staples on the college football calendar -- are dead now.

But what you can replace?

Texas A&M and Missouri's modest-to-OK results on the field since the Big 12 began.

TCU and West Virginia will be every bit the teams the Aggies and Tigers were on the field. They'll lack the history, sure. They'll lack the familiarity even more.

But they won't lack the success, however moderate it was for the Aggies and Tigers.

TCU coach Gary Patterson revitalized a historically mediocre program to unprecedented success, winning 11 games in six of seven seasons in the Mountain West Conference, including BCS bowl appearances in consecutive seasons in 2009 and 2010, capped by a win in the Rose Bowl.

TCU won't make winning 11 games an annual occurrence in the Big 12, but would Texas A&M have done much better with a similar schedule?

Meanwhile, West Virginia is 3-0 in BCS bowl games of its own, winning six Big East titles since 2003.

Could Missouri have done much more in the Big East?

Doubtful.

The Tigers have won eight games in six consecutive seasons, one of just a handful of teams to duplicate the feat. It won at least a share of the Big 12 North in three of the division's final four seasons before the Big 12 moved to 10 teams in 2011.

A 12-win season in 2007 was the highlight under Gary Pinkel, but the Tigers have yet to reach the BCS and never won a Big 12 title, getting blown out by Oklahoma in both Big 12 title game appearances.

WVU, though, won 32 games in the final three seasons under Rich Rodriguez and won 27 games in three seasons under Bill Stewart. Dana Holgorsen won 10 games in his first season.

The Big East isn't the Big 12, but Missouri won 63 games in that same span. Add up West Virginia's? The Mountaineers have 70 wins.

Why can't WVU step in and duplicate, if not exceed, what Missouri was able to do?

The Mountaineers can -- and will.

Meanwhile, the Big 12's most frustrating question -- why can't Texas A&M be a national power? -- is the SEC's problem now.

The Aggies have had all the facilities, all the support and all the resources necessary to become one. It has exactly one Big 12 title to show for it and still yearns for the days of R.C. Slocum. The legendary coach won four conference titles, but the program has been blanked since 1998.

TCU, meanwhile, is poised for a rise in the new Big 12. Recruiting will get a boost now that the school has major conference affiliation to offer prospects. Win totals will take a knock from recent totals but stabilize.

For the curious: TCU won 77 games in its past seven seasons. Texas A&M won 47 games in the same span.

Call it a small sample size. Call it a down period for the Aggies.

It's both, but now is now, and TCU looks more than capable to replace every bit of what Texas A&M brought the Big 12 on the field while the Aggies try to swim in the cutthroat SEC West, college football's toughest division.

The Big 12 is adjusting to a new world.

Off the field, the Aggies and Tigers will be sorely missed. To argue otherwise is foolish.

But on the field?

Credit the Big 12 on this one. The conference can easily say "Sayonara" without shedding a tear.