The Week That Was: American League West

This continues a division-by-division look at last week's transactions in baseball. See the National League East entry for ground rules.

HOUSTON ASTROS

Traded for: Nobody

Traded away: Nobody

Free agents signed: RP Luke Gregerson, RP Pat Neshek

2015 Impact: This is Houston saying, "We're done tearing it down, now we're building it up." The Astros had a pretty bad bullpen last year, with the worst ERA (4.80) and most blown saves (25) in the American League. Gregerson had a 2.12 ERA over 72 appearances for Oakland while Neshek's was 1.87 over 71 games for St. Louis. They're good additions as the Astros continue their climb toward respectability.

2016+ Impact: They're both signed through 2017, and the Astros have a team option on Neshek for 2018. They'll continue to contribute, barring ineffectiveness.

LOS ANGELES ANGELS

Traded for: SP Andrew Heaney, 2B/SS Josh Rutledge

Traded away: RP Jairo Diaz, 2B Howie Kendrick

Free agents signed: Nobody

2015 Impact: Substituting Rutledge for Kendrick is a big step down for the Angels, but Heaney is a top prospect. He was rated No. 30 in all of baseball prior to the 2014 season by Baseball America and Baseball Prospectus and No. 29 by MLB.com. The 23-year-old lefty compiled a 2.35 ERA over nine games with AA Jacksonville and a 3.87 ERA over 15 starts with AAA Las Vegas in the hitter-friendly Pacific Coast League (average ERA: 4.64). He struck out 91 in 83.2 innings had a strong 4:1 strikeout-to-walk ratio. He should be a contributor to the Angels rotation in 2015, possibly immediately. That being said, the loss of Kendrick makes the Angels less formidable at the plate in 2015.

2016+ Impact: There's a good chance they wouldn't have been able to keep Kendrick after this season had they not traded him, so over the long term, they're better off with Heaney and no Kendrick than with no Kendrick at all.


OAKLAND ATHLETICS
Traded for: SP Chris Bassit, C Josh Phegley, 1B-3B Rangel Ravelo, 2B Joe Wendle, IF Marcus Semien
Traded away: 1B-OF Brandon Moss, SP Jeff Samardzija, RP Michael Ynoa
Free agents signed: Nobody

The week before last I wrote over 2,300 words--that's excluding tables--explaining why I don't understand what the A's are doing. They're here. Let me add three more: I still don't.


SEATTLE MARINERS
Traded for: SP J.A. Happ
Traded away: OF Michael Saunders
Free agents signed: DH Nelson Cruz

2015 Impact: The Mariners are also a little hard to figure out. I don't like the Happ-for-Saunders deal--mediocre starter for one of the team's best hitters--and Rob Neyer explained why the Mariners probably over-valued Cruz. Still, given how excruciatingly bad the Mariners DHs were last year (they batted .190 with a .266 on base percentage and .301 slugging percentage and 171 total bases, all easily the worst in the league), Cruz should make them better.

2016+ Impact: I think Saunders is an OK player who won't be a free agent until 2017, while Cruz turns 35 next July. I could see the Saunders trade haunting the Mariners at least until his free agency.

TEXAS RANGERS
Traded for: RP Ross Detwiler
Traded away: 2B Chris Bostick, RP Abel De Los Santos
Free agents signed: Nobody

2015 Impact: I guess we can conclude that if the Rangers are trading two prospects for a 28-year-old reliever they must think last year's worst-in-the-league 67-95 record was a fluke. Actually, that's a little unfair: Detwiler was a pretty good starter for the Nationals in 2012 but became kind of the odd man out in the team's rotation, winding up in the bullpen. He's a reasonably good candidate to benefit from a change of scenery.

2016+ Impact: If the change of scenery works, this could be a nice pickup for the Rangers. If it doesn't, one of the prospects could make them regret this move.

Nolan Arenado, Ball Magnet

This morning I was scrolling through baseball stats at the mlb.com mobile site, and I noticed something curious. This is the list of major league leaders for assists: 

Rk		Tm	G	Inn	A ▾	Pos Summary
1	Troy Tulowitzki	COL	27	234.0	101	SS
2	Aaron Hill	ARI	29	260.0	92	2B
3	Starlin Castro	CHC	26	230.0	91	SS
4	Alexei Ramirez	CHW	29	260.0	90	SS
5	Brian Dozier	MIN	26	238.2	87	2B
6	Jimmy Rollins	PHI	24	204.1	87	SS
7	Nolan Arenado	COL	30	267.0	83	3B
8	Marcus Semien	CHW	29	251.0	83	2B-3B
9	Jose Altuve	HOU	28	249.1	81	2B
10	Ben Zobrist	TBR	30	237.2	80	2B-OF-SS

Provided by Baseball-Reference.com: View Original Table
Generated 5/2/2014.

Tulo, Hill, Castro, Ramirez, Dozier...all make sense. They're middle infielders, and middle infielders get a lot of ground balls. But there's the Rockies' Nolan Arenado tied for seventh. He's a third baseman. That seems out of place.

Arenado is in just his second year, but he's already won plaudits for his glovework. He won the National League Gold Glove last year as a rookie, and he hasn't let up this year. Still, how unusual is it for a third baseman to rank in the top ten in assists?

Really unusual, it turns out. As in, it hasn't happened since baseball expanded in 1961. The only third basemen in the 53 seasons since then to have finished in the top 20 in major league assists were Brooks Robinson (No. 13 in 1967), Ron Santo (No. 15 in 1967, No. 20 in 1966), Brandon Inge (No. 19 in 2006), Clete Boyer (No. 19 in 1962, No. 20 in 1961), and Graig Nettles (No. 20 in 1971). Nobody's been close to the top 10 until now.

Is this a fluke? I figure there are three things that could give Arenado a big advantage. First, handedness. Right-handed batters hit grounders to the left side of the infield more than left-handed batters, and managers load up on right-handed batters in order to gain a platoon advantage when they face lefties. Do the Rockies feature an unusual number of southpaw pitchers, resulting in opposing lineups full of right-handed batters, hitting grounder after grounder to third?

This year, lefties have pitched 37% of Colorado's innings. That's a lot. But it's not extreme: The Rangers, White Sox, Angels, Rays, Phillies, and A's all have had a greater proportion of innings pitched by lefties. So Arenado's pace isn't because he plays behind a steady stream of left-handed pitchers. 

How about the pitchers' tendencies themselves? Do Rockies pitchers, in an effort to keep batted balls out of the thin air at Coors Field, generate tons of ground balls? 

Again, yes, but it's not dramatic. Rockies pitchers have induced grounders on just under 49% of balls in play. That's high, but not highest: The Pirates, Phillies, Giants, and Dodgers have all gotten more. So that's not the explanation.

Finally, how about games played? Have the Rockies played more games than others, giving Arenado a chance to see more balls hit his way? Again, kind of yes. The Rockies have played 30 games so far, second-most in the majors. But other than the Tigers, every team's played at least 26. Maybe when the games even out, two of the players below him on the list above, Marcus Semien and Jose Altuve, will pass him. But that's probably it, at least on that basis. (And no, Arenado's assists aren't inflated by shifting, because, as Rockies Zingers points out, the Rockies do relatively little shifting.)

More likely, he just slows down. When a player's on pace early in the season to do something that's never been done before, the easy answer is to assume that he won't do it, either. But for a while here, I'm going to keep track of Arenado's assists and see if he can keep hanging with the middle infielders.