The Oakland Athletics are covering the third deck of the Coliseum, reducing the capacity of the stadium of around 34,000.

Taking the third deck out of play will make planning much easier. In addition, making tickets more scarce will encourage fans to purchase seats earlier and could increase the season-ticket-holder base, which is currently less than 10,000, one of the smallest in baseball.
More important, perhaps, is that the new baseball capacity will be 34,179 — which is just about the size the A’s would like to have if and when they get a new stadium. So, essentially, a smaller Coliseum will be a test run for a new ballpark.

This is a case where less appears to be more (Unix joke).