When discussing upper-level starting pitchers in Major League Baseball, the term "ace" is thrown around with some level of frequency. Thus, when James Shields signed with the Padres early Monday morning, we saw lots of ace talk.

There's nothing wrong with it. My colleague David Brown wrote an excellent piece on Shields now fronting the San Diego rotation and discussed how he's not a prototypical "ace." He's right. The way most people throw the term around, I don't think most would include Shields in that conversation. But some others would call him an ace. It just depends upon the point of view.

Seriously, "ace" is such an arbitrary term in baseball. Every individual person settles on his or her own definition of what an "ace" is. If we were going to be less subjective about it and more objective, wouldn't an ace simply be a top 30 pitcher in baseball?

Think about it. There are 30 teams. Each have a number one starter. Ace means one. So the best 30 pitchers are aces. That doesn't mean every team has exactly one. Some teams can have zero and some more than one. Still, with 30 teams, it seems to me it's reasonable to say that the top 30 pitchers are aces, just as the pitchers ranked 31-60 -- by whatever means one wishes to use in ranking them -- would be the No. 2 starters. The 61-90 starters are threes and so on.

I actually saw someone a few days ago suggest Shields was more like a "decent two or maybe even a three." That's ridiculous. There aren't 60 better pitchers than Shields.

Regardless, though, let's play around with the term and the pitchers.

By the definition of some, there are only a handful of aces in the majors: Clayton Kershaw, Felix Hernandez, Max Scherzer, Adam Wainwright, Chris Sale et al. Perhaps the people who don't consider Shields an ace would say Justin Verlander isn't one anymore and Corey Kluber has to prove he wasn't a fluke last season.

Are both of these guys aces?
Are both James Shields and Felix Hernandez aces, even if King Felix is far better? (USATSI)

In going with the top 30, though, I feel like the easy picks for the "ace" label are as follows (I'll leave Shields out and these are not ranked):

Kershaw, Hernandez, Scherzer, Wainwright, Sale, Kluber, David Price, Stephen Strasburg, Jordan Zimmermann, Madison Bumgarner, Johnny Cueto, Jon Lester, Yu Darvish, Cole Hamels, Jose Fernandez (not for this year due to injury, though) and Matt Harvey (maybe, injury a concern).

That's 16 guys. Let's throw in the following:

Cliff Lee, Masahiro Tanaka (maybe), Zack Greinke, Henderson Alvarez (look up his numbers if you disagree) and even Verlander if you want. That's 21.

Can we really come up with nine more pitchers that we'd definitely rather have in 2015 than Shields? I could see arguments for Jeff Samardzija, Sonny Gray and possibly a few others (Doug Fister, Anibal Sanchez, Phil Hughes, etc.), but you'd be hard pressed to 100 percent convince me Shields easily falls outside the top 30 starters in 2015.

Keep in mind, this guy hasn't missed a turn in eight years. In the past four seasons, he's posted a 3.17 ERA (124 ERA+) while averaging 233 innings a year. Few have that resume.

So I'm calling Shields an ace.

That doesn't mean Shields is the same as King Felix or Kershaw or what Bumgarner was in October. Shields is not on that level. There are different degrees of everything, though. The Hall of Fame has Babe Ruth but it also has Jim Rice. Just because both are there doesn't mean baseball fans are stupid enough to believe they were equal players. Apply that line of thinking with "ace" and how it literally means No. 1 starter and there are 30 of those in Major League Baseball.

Shields isn't an elite-level starting pitcher, but for me, he's good enough to call an ace.