Even though the Tigers still had Justin Verlander signed for two more years, they signed their right-hander to a huge contract this spring that essentially made him the highest-paid pitcher ever. He’ll receive $28 million per year every year from 2015-2019.

That’s kind of a scary thought right now, isn’t it? Verlander gave up seven more runs Thursday in a loss to the White Sox. He fell to 10-8 with a 3.99 ERA for the season. Six times this year he’s allowed at least five earned runs in an outing. Only Mark Buehrle, R.A. Dickey and Jeremy Guthrie, with seven such outings, have done so more frequently.

That’s certainly not to say Verlander has been all bad. He has eight outings in which he’s allowed one or no earned runs, including two this month. His ERA ranks just 24th in the AL, but he is sixth in strikeouts and seventh in innings pitched. He’s hardly been a liability.

What is worrying is that Verlander’s average fastball has tumbled to 92.7 mph this year, according to Fangraphs’ Baseball Info Solutions data. He came in at 94.3 mph in 2012, and he was in the 95-96 mph range each of the three years before that.

Verlander isn’t falling apart, but it seems pretty likely that his peak has already come and gone. Before his Cy Young season in 2011, his career best ERA in six seasons was 3.37 and WHIP was 1.16. The mid-3.00 ERAs seem like the better bet for the future than the mid-2.00s of 2011 and ’12. And that’s probably the optimistic scenario for the Tigers, considering that he was baseball’s hardest working pitcher from 2009-2102.

The Tigers still had Verlander under control for two more years when they extended him this spring. Technically, it was announced as a brand new seven-year, $180 million contract, but in reality, it was a five-year, $140 million extension for 2015-19. At that rate, the deal had very little upside. Verlander needs to remain one of baseball’s best pitchers to justify that kind of salary, and that’s an awful lot to ask. There aren’t many pitchers in history who can claim to have had an eight- or 10-year run as one of baseball’s best.

If not for the extension, the Tigers would currently owe Verlander $27 million through the end of 2014. That sounds a whole lot better to me than $167 million through 2019.