Because this team isn't as bad as you and everyone else assumes just because it's been a bad year. Yes, some key components have had down years and they needed youth. They were also locked into this team last offseason due to salary constraints. Now they have money coming free, have young pieces that will be given a chance at the MLB level (Jimenez, Jones, Candelario). They make a major bullpen addition and add an arm with upside they can easily compete in the #### show that is the central. The MLB had ~18 teams within 5 games of a wildcard birth at the deadline. The question is why the #### wouldn't we try to compete? You get into the playoffs and anything can happen. If Upton opts out, that would be the move that would make me believe that they would highly struggle to be in the thick next year. And there is even upside to that as it will give freedom to spending where they want to spend. I don't think it is too outlandish to see Norris develop into a quality starter despite the superior analytical analysis of some fans in this thread. Mahtook was one of the best players in baseball in July. I am far more bullish about this team then most fans right now.
The areas I am least excited about are the middle infield and what to do with VMart. I'm guessing VMart stays because it's a lot of salary to eat even if they could get something in return and he was to waive his 10/5. This means that Nick will probably be who goes to a corner OF position where I anticipate he will also be subpar defensively out there. Iglesias I am not a huge fan of but I haven't put much effort into seeing how good he is defensively to see if he makes up for the atrocious offense. Machado has shown some ability to hit but I doubt he's a solution either. It would probably be best to keep Kinsler into next season unless they have some plan to get a 2B before next year.
I don't think they will contend for a couple years because of a few factors.
1. The payroll is going to go down, Mike Illitch was an owner and a fan and wanted a world series title before he went out and didn't care about spending extra money to do it.
2. There are too many unknowns for 2019, Verlander might be done, or he might be an ace still, but I am not counting on it, Kinsler will be gone, Upton maybe gone, JD is gone, Miggy will be older and if the last few years have shown us anything he is going to be hurt a lot, Zimmerman could be done, and we have no idea if Boyd, and Norris will work out, plus the bullpen.
3. The central might be bad this year, but they won't stay bad, and actually they aren't as bad as you think. The Twins are up and coming, the White Sox just got a lot of young talent that could start coming into their own in a couple of years, and Cleveland will still be good for a couple more years.
4. I would slow down with the Mahtook thing, I hope he works out, but Chris Shelton, Boesch. You can't judge a player off of one month.
5. Didn't Nick try a corner outfield spot in the minors for a while and it was a disaster?
Sure if everything falls into place you could have 2006 all over again, but you can't count on that.