By Doug Upstone

As a major league pitcher reaches his 30's and has been toiling at his craft as a top-flight hurler for years, his body will start to lose elasticity. The joints and muscles that allowed a blazing fastball, a wicked curve or a nasty slider, are not quite the same in many cases. The ace of the staff has to learn to pitch differently. A changeup or cutter adds greater deception and adjusting the hitter's eye level pitch after pitch takes on even greater importance, not being able to just blow away batter's start after start.

Here we will look at which aces, in alphabetical order, current or former, should be trusted the rest of the season by those betting baseball.

Jake Arrieta, Cubs - 31 years old

There has been talk all season about the dip in velocity, his complicated delivery causing more breaking balls to hang and the wear and tear of consecutive postseasons. Arrieta is still striking out a hitter an inning, and if he can find a little more command and not work as deep in counts, he and the Cubs should be money. Betting Factor - Trust

Zack Greinke, Diamondbacks - 33

After an unsettling 2016, Greinke is throwing like the pitcher Arizona signed to a big contract. Whether it was feeling the pressure from big deal or boredom from being on a bad team, Greinke has rebounded. His fastball is no longer in the mid-90's, but his array of off-speed pitches and placement are dazzling to watch. Betting Factor - Trust

Cole Hamels, Rangers - 33

Hamels has just come off the DL and his first game back was not pretty. He gets a pass for being rusty, yet even before the injury this season, his strikeouts were down and free passes were up. We started to see this last season and opposing hitters have been taught to identify tosses from Hamels that are likely to balls and lay off. Maybe the left-hander will turn it around, and maybe not. Betting Factor - Uncertain

David Price, Red Sox - 32 on 8/26

Since arriving in Boston, it has not been a smooth transition for Price. Last year he got off to a poor start, and though he finished strong, his WHIP and ERA were at their highest levels since his first season as fulltime starter with Tampa Bay in 2009. Price was injured in spring training and is still getting settled in, yet homers and walks allowed are a growing concern, you'll never know what his scores and odds wil be. Betting Factor - Uncertain

Max Scherzer, Nationals - 33 on 7/29

Scherzer is one of the game's top aces and shown no signs of slowing down. Despite an above average record, his numbers are on track for career-best. Granted, he was in similar form last year and slid the last two months, still, his loose body and array of pitches keeps him in a group just behind Clayton Kershaw. Betting Factor - Trust

Justin Verlander, Tigers - 34

No longer possesses the upper 90's heater he could blow guys away with upstairs with two strikes. Justin Verlander still strikes out a lot of hitter's, however, but command is now an issue. He's down to 2-to-1 strikeout/walk ratio after being 3/1 or 4/1 most of his career and leaves more pitches over the plate, which are nailed. Betting Factor - Untrustworthy

Adam Wainwright, Cardinals - 36 on 8/31

Age and injuries the last few years have robbed him of previous skills, and Wainwright relies heavily on change-ups and deception to get hitters out now. Has sunk to middle of the rotation hurler and at times been painful to watch. Betting Factor - Untrustworthy

Comment about what current or former aces should still be trusted