From a friend of mine yesterday:

IIRC you were higher on Texas than most pre-season. Interested to hear your thoughts now. Is the ERA at all sustainable in Arlington given the lack of Ks from the staff?

The Rangers have made themselves into a story over the last week, sweeping the Angels at home to push themselves to 23-14, with a seven-game winning streak and a four-game lead in the AL West as we near the quarter-season mark. There’s a short answer to the above question, but I think it’s better to use it as a jumping-off point to ask some others.

How are the Rangers 23-14?

Perhaps this could be phrased as “why aren’t they 18-19, or about where they were ‘supposed’ to be?” When you put it that way, you see that they’ve outplayed expectations by about five wins so far, so that even if they were to play to expectations the rest of the way, they’d be in line to stay above .500 and contend in a weak division all year long. This is important; the Rangers may have changed their narrative by just outplaying expectations for six weeks.

The Rangers have scored 209 runs and allowed 179, so they’ve slightly outplayed their run differential, which pegs them closer to a 21-16 squad. They’ve also played a relatively soft schedule, something that can be measured loosely by the difference between their third-order and second-order records in the Adjusted Standings Report. Their gap of 1.8 is the largest in the game. Their third-order record of about 20-17 shows that the gap between their actual and expected records is about half good fortune and half performance.

Where is the Rangers’ good performance coming from?

Their team EqA is .269, third in the league behind the Rays and Blue Jays. That figure seems reasonable, and as you look at the individual performances, there even seems to be room for improvement. Jarrod Saltalamacchia, Chris Davis, and Josh Hamilton are all under expectations, and while Ian Kinsler and Michael Young among the regulars and bench stars Andruw Jones and Omar Vizquel are above, the overall offense seems to have more growth potential, because of the high-upside young players, than decline potential.

The Rangers’ run prevention has been a bit of a surprise. The team’s starters are fifth in the AL in Support-Neutral Value, and the relievers are third in WXRL, with most of the same personnel that ranked 14th and 10th in those categories a year ago. Kevin Millwood has a 2.93 ERA in eight starts, and Matt Harrison had a long shutout streak and is at 4.23 in his seven starts. Scott Feldman has a 2.17 ERA since joining the rotation a month ago. Closer Frank Francisco didn’t allow a run in 14 appearances before hitting the DL; waiver claim Darren O’Day has a 2.00 ERA in 11 outings; injury case Jason Jennings is at 3.24 in mostly low-leverage relief.

A bigger reason for the run prevention is an improved defense that has risen from having the worst Defensive Efficiency in baseball to the fourth-best overall and second-best mark in the AL. Since moving into The Ballpark in Arlington in 1994, the Rangers have never converted more than 69 percent of balls in play into outs, and they haven’t had a positive Park-Adjusted Defensive Efficiency since 1990. This year, they have a DER of .713 and a PADE of +3.33, leading the AL. Put simply, they’ve gone from a bad defense to a very good one.

How much of the Rangers’ success is sustainable?

The Rangers are third in batting average and strikeouts, first in home runs, yet just 13th in walks and 11th in OBP. The mix there is unstable, reflecting a team that is performing extremely well on contact, and needs to do so to have enough runners on base. Eric Seidman looked it up and found that the Rangers were the best team in MLB on contact last year, hitting .358 and slugging .585, which was the best performance of any team in 2007 or 2008. This year, they’re hitting .360 and slugging a ridiculous .641. That’s nearly 60 points higher than any other team has slugged on contact in the last three years. This isn’t sustainable, or anything close to it.

Whether the Rangers start drawing some walks to bolster the offense as the on-contact numbers drop will determine how many runs they score for the rest of the season. They are almost certainly in for a drop in their production.

All of those fancy ERAs I mentioned earlier are almost entirely a function of that great team defense. The Rangers are last in the AL in strikeouts and last in K/BB, two leading indicators of pitching performance. A number of the individual pitchers have rates that don’t pair well with their ERAs: Harrison has 24 strikeouts and 13 walks in 44 2/3 innings; as a starter, Feldman is 13:8 in 29 innings and has yet to allow a home run. Some of this is the effect of the improved defense-the more outs the fielders make, the fewer strikeout opportunities there are-but it doesn’t seem likely that they can keep runs off the board as well as they have to date with the current personnel.

The defensive improvement is real. Upgrading from Michael Young to Elvis Andrus at shortstop, and from Hank Blalock et al. to Young at third base, is going to end up being worth 30-40 runs over the course of the season. Young’s hardware aside, he wasn’t a good shortstop, and Andrus is; Andrus is going to have an argument for a Gold Glove Award in his rookie season. The Rangers can continue to prevent hits on balls in play in the infield; the one thing I might worry about is the potential for the 20-year-old Andrus to lose a step as he plays his longest season ever through the heat of a Texas summer.

Where can the Rangers improve?

Chris Davis has played better of late, but at some point the team might look to replace him with one of their many hitting prospects, perhaps Max Ramirez, perhaps even 2008 first-round pick Justin Smoak. It seems radical, but Davis’ plate approach is the Rangers’ problem in a nutshell, and they’re going to need some baserunners when the on-contact performance regresses.

The Rangers could use at least one additional reliever. That could happen in the same manner that they added Derek Holland, should Neftali Feliz continue his development at Triple-A. Outside of Francisco, the Rangers don’t have a shut-down relief pitcher, and that weakness is a tactical problem late in games. Whether they should be worried about that in what is the year before they’re supposed to be taken seriously is an open question; however, given their internal depth and the price of relievers at the trade deadline, there are a number of ways in which they might solve this if an AL West title is within their reach.

The Rangers could help themselves more by moving Josh Hamilton to a corner and allowing Andruw Jones to get more time in center field. Hamilton isn’t a good center fielder, and I think some of the Rangers’ improved defensive stats stem from their missing Hamilton for 40 percent of the schedule. David Murphy doesn’t do anything well enough to be more than a bench player, and a Hamilton/Jones/Cruz outfield, with Murphy and Marlon Byrd spotting people, would be an improvement. If Hamilton continues to play center field, their overall defense won’t be quite as good, and coupled with the possibility that Andrus tires, leaves their key strength so far this season, this defense, vulnerable.

The biggest reason to be optimistic about the Rangers-as opposed to, say, the Blue Jays, who I’ve been pretty pessimistic about-is that the Rangers aren’t trying to win the AL East. The competition in the AL West isn’t very good, with the A’s turning in a terrible start, the Mariners improved but shy of dangerous, and the Angels dealing with an assortment of injuries. The Angels are still the favorites, because they’ve hung around through the rough start and will now get back two very good starting pitchers. The Rangers’ have enough trade bait that if they want to go all out to win this year, they can, but the stronger approach for them is to contend for as long as they can, while keeping the focus on 2010 and beyond. The talent base here is going to be the best in the West for a long time to come, and whether they win the division in 2009 or not isn’t as important as developing the young talent and making sure that it’s ready to be the core of a potential dynasty a year from now.