SCOTTSDALE, Ariz. — The truth is that James Shields has not done much for the Royals.

Not on the field, anyway. He’s thrown a total of four innings, 51 pitches, none of them curveballs. The Royals have $21 million and the tantalizing talent of Wil Myers riding on Shields being the reason they win real games instead of these fake ones.

So, basically, what we’re seeing on the field so far is the equivalent of a nice and limber pregame stretch. What we’re hearing in the clubhouse is something entirely different.

“It’s night and day,” Billy Butler says, “from where the pitching staff was to where it is now.”

The Royals limped through a hugely disappointing season in 2012, largely blamable on one of the worst starting rotations in recent baseball history. What the Royals’ starters lacked in ability to eat up innings, they made up for by surrendering gobs and gobs of runs in those innings.

You know that Shields is the centerpiece of a complete rotation makeover. He is the Royals’ best pitcher since Zack Greinke, a guy you can call a No. 1 starter without snickering. This is like replacing one of those old tube televisions with a newer model, stale milk with a fresh carton or, come to think of it, Matt Cassel with Alex Smith.

The Royals won’t have their division’s best rotation, but unlike last year, they will have a chance. For the first time in a generation, the Royals should have more than half their games started by pitchers with a recent history of being good. These are small compliments, of course, but you have to start somewhere.

Royals fans don’t need to be reminded of the nightmare, but by some advanced metrics, the team would’ve actually been better off with a rotation full of minor leaguers named Fred than the nightly mess they ended up with.

Last year, the six most-used starters made it just 776 innings with a 5.06 ERA. This year, Baseball Prospectus projects them for 935 innings with a 4.40 ERA. The improvement translates to about five wins in BP’s system. That system is based on a variety of outcomes, so the improvement could be eight to 10 wins if nobody suffers a major injury or goes all Jonathan Sanchez.

Even now, so early that college basketball’s regular season is still going on, you can see glimpses of why general manager Dayton Moore invested so much for Shields (and Wade Davis, who should be the fourth starter). The Diamondbacks struck out twice and hit virtually nothing hard against Shields in three scoreless innings. None of the outs left the infield.

Shields doesn’t want to think too far ahead on any of this. Real games are still nearly a month away. The way he puts it, success right now is judged simply by throwing the predetermined amount of pitches without injury or mechanical problems. So far, so good.

It’s not just Shields, either. Ervin Santana pitches today, and while he was dreadful last year, he was one of the American League’s better pitchers the two years before that. Jeremy Guthrie pitches on Friday, and his success in two months with the Royals last year provides confidence through the organization. Davis provides legitimate hope.

The Royals created their most promising season in at least nine years with a series of rotation moves symbolized by the fact Luke Hochevar and Bruce Chen — last year’s candidates for the opening-day start — are now competing with Luis Mendoza for the last rotation spot.

This is enough for a virtual consensus within the industry that the Royals will be better. Perhaps, if things fall right, a contender. But there is a hidden danger in here. The rotation is remade, and that’s important. It also hides that the offense stunk, too.

The offense should improve on its own. But if it doesn’t, a better pitching staff won’t mean much.