Richard Jacobs bought the naming rights of the new Indians Park before the 1994 season; he then re-named it Jacobs Field, after both himself and the real estate company he owned. The name didn't sound corporate, like PNC Park or Qwest Field or Network Associates Coliseum, but more along the lines of Busch Stadium, a park with an aesthetic corporate name.
After Jacobs sold the team to Larry Dolan, he retained naming rights through the 2006 season. The Indians couldn't get a replacement in time for 2007, so the old name was kept through that season. But now the team has found a replacement, the name of one of the few remaining Fortune 500 companies left in the area. The new deal will net the Indians, after initial costs, about $48M over the next 16 years. Needless to say, it won't dramatically change the team budget, but it's still a nice little revenue stream.
To those who grew up with Jacobs Field, including myself, it will take a long time to think of it as anything but The Jake. By the time this current contract runs out, the stadium will have been known as Progressive Field longer than its original incarnation, and time will probably have overcome human stubbornness. It's not a blatantly obvious company name, in fact most people would associate the word more with the forward movement of institutions and society than car insurance. It could have been a lot worse.