Non- responsive to my point about teams getting worse (intentionally) in the second half while striving to make themselves better in the future. I'm not saying the Astros are going to do it. I'm saying someone in the NL plays close to 600 ball post ASB, and I'd not be surprised if it was 2 or 3 teams.
I wasn't seeking to specifically respond to your post, but now that you mention it, I don't see how it's not responsive. Wouldn't the effect you're positing ("teams getting worse (intentionally) in the second half") have applied in the seasons 2000 to 2006 as well as 2007? I would think so.
That being the case, then demonstrating the magnitude and frequency of teams improving in the second half for those seasons should reflect the same effect you're talking about for 2007. Unless you think the "weakness" factor is that much more pronounced in the 2007 National League, which I'd need to see data to support.
From 2000 to 2006, roughly a fifth of teams (43 of 210) played .590+ in the second half. Just five of those teams were sub-.500 in the first half, however. They were:
2001 Mets (38-51/44-29)
2006 Phillies (40-47/45-30)
2003 Twins (44-49/46-23)
2003 White Sox (45-49/41-27)
2006 Angels (43-45/46-28)
Again, I'm not saying the 2007 Astros won't be the sixth such team since 2000 to do that, since what a bunch of other teams did in the past is not determinative of what any team will do in the future. But based on recent history, the probability of a 39-50 team at the All-Star break playing something close to .600 ball in the second half isn't very high.
You are certainly correct that two or three National League teams are likely to play .600 ball in the second half, however. That happens virtually every season.