One week after examining pitching tools, laying out my rankings (and reasoning) in eight categories, I look at position players today. Here are my rankings in the four key hitting/speed tools that scouts use to evaluate players.

Hit tool

1. Paul Goldschmidt, 1B
Arizona Diamondbacks
Relevant 2015 stats: .334 BA (leads MLB), .447 OBP (second), .570 SLG (fourth)

The hit tool is the most nebulous of the five major tools for position players, and it's the hardest to scout. (How often do you hear about a five-tool player, only to discover he can't hit? Well, guess what: He was a four-tool player and didn't have the one that counts.) Is the hit tool the ability to make contact? To put the ball in play in a way that it's less likely to be fielded? To make harder contact, now that we have exit-velocity data? I think it's some ambiguous combination of all of those, with a bit of plate discipline and/or pitch recognition involved as well.

But that doesn't make it any easier to identify, especially in amateur players. Even for prospects, we'll often talk about how "he can hit" and "he can't hit," but without a lot of detail, because it's hard to be specific when evaluating a skill without clear benchmarks. That said, the five guys ranked here can hit. Goldschmidt is the exemplar, a guy who hits all kinds of pitching, makes hard contact, controls all parts of the zone, and works the count. He's physical and cerebral, and I think he's as hard to pitch to as anyone in the game. Check back a year from now and Chicago Cubs rookie Kyle Schwarber might be on this list.

2. Mike Trout, OF, Angels

3. Bryce Harper, OF, Nationals

4. Jose Altuve, 2B, Astros

5. Buster Posey, C, Giants

Power tool

1. Bryce Harper, OF
Washington Nationals
Relevant 2015 stats: 30 HRs (leads NL), .452 OBP (leads MLB), .638 SLG (leads MLB)

Power is easier to identify and to measure after the fact. You can see it in batting practice and in games, and we all agree on what power means, although there is a distinction between raw power (what the player can physically do to the baseball) and game power (how it plays, which ends up factoring in ability to hit and work the count). Harper and Giancarlo Stanton could be 1-2 or 2-1. Both were criticized for having "long" swings when they were teenagers, but both turned out to be advanced hitters too, so their grade-80 raw power could play as grade-80 game power. Check back a year from now and the Rangers' Joey Gallo will probably be first on this list.

2. Giancarlo Stanton, OF, Marlins

3. Mike Trout, OF, Angels

4. Jose Bautista, OF, Blue Jays

5. Kris Bryant, 3B, Cubs

Speed tool

1. Billy Hamilton, OF
Cincinnati Reds
Relevant 2015 stats: 53 SBs (leads MLB), plus-14.2 ultimate zone rating on defense (third in MLB)

Speed is the easiest tool to evaluate since it's about one thing that is easily measured with a stopwatch. That said, there are runners who are faster while underway than they are home to first -- Jacoby Ellsbury has always been like that -- which means simply timing a batter from the moment of contact till the moment his foot hits the bag at first isn't always accurate. Terrance Gore is probably in the top three in organized baseball in speed, but he can't hit a lick and isn't even a good defensive outfielder, keeping him out of the majors and off the list. Mike Trout would have been on here a year ago, but he seems to have lost a good bit of his foot speed this season. Check back a year from now and Hamilton will still be atop this list, forever and ever amen.

2. Dee Gordon, 2B, Marlins

3. Billy Burns, OF, Athletics

4. Kevin Kiermaier, OF, Rays

5. Byron Buxton, OF, Twins

Plate discipline

1. Joey Votto, 1B
Cincinnati Reds
Relevant 2015 stats: 90 walks (leads MLB), .310 BA (15th), .437 OBP (third), 0.98 BB/K ratio (fourth)

Not strictly a tool in the sense of the five tools (hit, power, run, field, arm), but a critical one for evaluating a hitter's ability to put the hit and power tools to use in games, plate discipline should encompass the ability to distinguish a ball from a strike and recognize pitches, and the willingness to work the count. It's not just drawing walks, no matter what Moneyball and its detractors led you to believe, but walks are good things and we like them. Votto is actually just an algorithm with a bat and a helmet, much to the consternation of Reds fans and others who can't get over "the RBIzzzzzz!" and recognize the historically great approach Votto brings to every at-bat.

2. Ben Zobrist, OF/2B, Royals

3. Michael Brantley, OF, Indians

4. Anthony Rizzo, 1B, Cubs

5. George Springer, OF, Astros

Springer's presence on this list might surprise you, but his plate discipline -- specifically the things I mentioned above -- is great. He rarely chases pitches out of the zone and he recognizes off-speed stuff well. His lack of a two-strike approach leads to the low contact rate, but I don't think that's part of plate discipline. Check back in a year and Carlos Correa may be at the top of this list. OK, maybe second. Votto's not going anywhere till he hangs 'em up.