There are theories and clichés that might help explain baseball’s parity top to bottom, compared to other major professional sports. The one I like the most is, “Momentum is as good as that night’s starting pitcher.” What this parity has produced through the first third of the 2012 season is 20 of 30 MLB teams within five games of a playoff berth. Just one team, the Dodgers, has a win percentage above .600 and just three — the Twins, Cubs and Padres — have a mark below .400.

Compare that to the other major sports that keep track of winning percentage in the standings. This past season in the NBA, nine teams had a winning percentage above .600 and 10 were below .400. The numbers were exactly the same in the NFL, although there are 32 teams in football, compared to 30 in basketball and baseball. Baseball is clearly the major sport with the most parity.

“I think it’s that you see good teams every time you walk on the field,” Blue Jays manager John Farrell said. “We’re going to see another team in the American League Central we haven’t seen. They’re playing extremely well. Within our division, I don’t think there’s one team that looks at another and says we can just throw our hats on the field and walk away with a win.”

It’s amazing that heading into Tuesday’s action, the combined home record of all 14 AL teams was nine games below .500 while on the road the league stood 15 games above. That difference is explained by interleague play. The White Sox were 14-14 at home, while the Jays’ record at the Rogers Centre stood at 16-12. The NL was 35 games above .500 as a league at home.

“Maybe the guy in centre field in a white shirt isn’t in every ballpark,” Farrell joked when asked to analyze. “As for parity being consistent throughout the league, the numbers bear that out, and for a wide range of reasons, whether it’s been individual performance, or lack of in some cases, where teams have been hit harder with injuries in some cases than others. You look at three games separating our entire division, that just in a snapshot might reflect all of the American League.”

The standings were so tight that as of Tuesday afternoon the Jays were tied for last place in the AL East, three games out of first and 1 1/2 games behind the Yankees for the second wild-card spot. There were 10 teams in each league within five games of a post-season berth. Certainly that should change the landscape as the July trade deadline approaches.

“Coming out of the weekend, all over baseball, there might be 20 teams within maybe five games of a wild card,” Farrell said, with his number bang on. “So, yeah, I’m sure every GM, many teams are more optimistic with the position they’re in and I’m sure those conversations at the deadline will be much more in depth and the value or the price of acquisitions might even be a little bit higher.”

That would include Jays GM Alex Anthopoulos. As long as his team continues to bounce around between .500 and five games over, they will remain in the wild-card race into the final month of the season. If you’re in the race on Sept. 1 and with no Type A or Type B free agents to buy and sell to stock your farm systems, there may not be much going on in July.

Normally, the Jays might have been busy fielding offers for veteran bullpen arms like Darren Oliver, Francisco Cordero or Jason Frasor, or even second baseman Kelly Johnson, eliglible again for free agency at the of the season. But with everyone hanging around on the edges of the wild-card race, even teams like the Jays would be looking for immediate help instead of futures.

What’s might help the whole July trading process is that the deadline for siging draft choices out of the June entry procedure has been moved up to July 13 this year, meaning that will be out of the way for GMs, allowing teams to know how much money they have for major-league talent. Plus, if they fail to sign one if their top draftees, do they have to make a major-league roster move to excite their fan base? That never happens, does it? In any case, it will be interesting to watch all this unfold because for everyone in MLB, it’s all new under the new CBA.

But as long as everyone’s still in the playoff race, it might remain quiet.