The Texas Rangers came within one strike of winning their first world series two times. Going into free agency they don't need to do a lot if they want to get back. Two things they could improve on though are starting pitching and first base.
The Rangers had four really good starting pitchers this season. They were C.J. Wilson, Matt Harrison, Alexi Ogando and Derek Holland. Combined all four pitchers posted 17.3 WAR. The problem is Alexi Ogando probably won't be that good next season and C.J. Wilson may not even be on the team. Wilson has stated that he would like to return to the Rangers but who knows if that will turn out if the Yankees start throwing cash at him. If he leaves the Rangers wouldn't have a ton of options.
They could look at Roy Oswalt but he's stated in the past that he's a National League guy. Or they could look at Japanese-Iranian sensation Yu Darvish. Darvish is a 25-year-old pitcher who pitches for the Japanese team Hokkaido Nippon-Ham Fighters. Darvish is 6'5" and weighs 220 lbs, he can easily put on some pounds. Darvish throws five pitches. He has a 4 seam fastball that is usually between 91-94 mph but can top out at 97 mph. He has a slurve, two seam, cutter, curve, splitter and a change-up as well. In his six year career Darvish has 974 strike outs and 247 walks. For what it's worth he's had an ERA under 2 for the last four seasons. He'll be expensive as well and the Rangers have money to spend. Check out this article by Dave Cameron of Fangraphs about how much Darvish should get paid. After those two there aren't really ace like pitchers on the market and that's what Texas would need if they lost Wilson. They could also ask Tampa Bay about Shields but he would come at a cost.
Texas also could use a first basemen going into next year. Mitch Moreland showed he has power potential (.155 ISO) But his .317 wOBA is dreadful. There just happens to be two very good fist basemen on the market this season. I don't think they'll sign Albert Pujols but I do believe they have a legitmate shot at Prince Fielder. With Adrian Beltre, Nelson Cruz, Michael Young and Mike Napoli all right handed Prince Fielder could slide right in with Josh Hamilton and supply power from the left side. The past 6 years Fielder has totaled 23.4 WAR but one year he only had 62 PA with .1 WAR and the other two he had a combied 3 WAR. This past season he posted 5.5 WAR which was his second highest in his career. His highest was in 2009 when he posted 6.4 WAR. If Fielder posted 5.5 WAR, 6 WAR, 5.5 WAR, 5 WAR, 4.5 WAR over the next five years he'd be worth he would be worth $106 million dollars in value. If the Rangers could get him for 5 years $100 million they'd have themselves a nice deal. At 28 years old Fielder still is well in his prime and should still put up huge numbers. It would probably cost the Rangers 5-6 years at a little over $130 million dollars though.
Overall the Rangers are a really good team and don't have to make a ton of changes. I fthey could get C.J. Wilson back and sign Fielder they'd be right in the mix for a third world series appearance.