As of this writing, the Texas Rangers are 40-25 and have their biggest lead in the AL West since May of 2013. It would be easy to say that everything is rainbows and lollipops in Arlington, but there is one glaring weakness this season. The bullpen. It is not that the Rangers do not have any good relief pitchers. They do. In fact they have four. Sam Dyson, Jake Diekman, Matt Bush, and Tony Barnette have combined to pitch 97 1/3 innings this season for an ERA of 2.31, while striking out 90 and walking only 24.

The problem is that you cannot pitch the same guys game after game for 162 games. You need a second tier of at least decent relievers. This is where the Rangers have failed so far this season. The Rangers bullpen, minus the four pitchers mentioned above have combined to pitch 101 1/3 innings for an ERA of 7.82, while striking out 75 and walking 48.

Last season at the trade deadline, the Rangers acquired two impact relievers (Dyson and Diekman) at relatively little cost to improve their shaky bullpen. So the precedent is there for the Rangers to be able to improve their bullpen mid-season. One thing that may help the bullpen immensely is the return of Keone Kela from injury. He is expected to start throwing from a mound next week and should return by the end of July. Kela pitched 60 1/3 innings last season with an ERA of 2.39, while striking out 68 and walking 18. There is no guarantee that Kela will return to his old self when he gets healthy though. So realistically, the Rangers need to make some kind of improvement to the bullpen.

There are a few decent arms in the upper levels of the minors that the Rangers will likely call on to pitch a few innings in relief throughout the rest of the season, but the real improvement is likely to come from outside the organization. There has been talk of the Rangers acquiring Andrew Miller from the Yankees for a top level prospect such as Jurickson Profar or Lewis Brinson. I am of the belief that, because of their unpredictability and relatively minor impact, a team should never give up someone with as much upside as Profar for a relief pitcher. The Rangers proved last season that you can improve your bullpen midseason through trades relatively cheaply.

I have decided to make a list of relief pitcher trade targets that the Rangers may look at acquiring this season. I limited the list to pitchers that are on teams that are at least 5 games out of a playoff spot, are on a team that is not in the AL West, and are either a free agent or arbitration eligible in 2016 or 2017. That narrows down the list to the types of players that are normally dealt at the trade deadline.

The way that I whittled down the list of trade targets from all of those that qualified to the ones that would actually help the Rangers is a bit complicated, but I will try to explain it in the best way I can. Earlier this season I created a simulation model that uses Statcast data such as exit velocity, batted ball distance, and launch angle, as well as PitchFX data such as pitch location to attach an “event value” to everything that happens on a baseball field. As an example, if Rougned Odor hits a ball 232 feet at a launch angle of 24 degrees to a certain part of right field, that ball may have a single value of .4 (meaning that 40% of balls that are similar to that one become singles), a double value of .2, and a triple value of .03.

Once I have the event values for each play that a particular player is involved in, I add them up and create an “expected stat line” from those values. My tests have shown that these “expected stat lines” more accurately predict how the player will perform throughout the rest of the season than his actual stat line. The three event values that I am interested in for this post are the three that pitchers have the most control over: strikeouts, walks, and home runs allowed. Once I add up all the strikeouts, walks, and home runs allowed that a pitcher should have based on the pitches he has thrown and the batted balls he has allowed, I plug them into the formula for FIP. That formula is (13*HRA + 3*BB – 2*K) / IP + 3.20 (where HRA = home runs allowed, BB = walks, K = strikeouts, and IP = innings pitched). FIP is designed to show what a pitchers ERA should be based only on the things that he most controls. I call my new version of FIP “SCERA” for “StatCast Earned Run Average.”

I ran the numbers for every pitcher that plays for a team that is at least 5 games out of a playoff spot, is not in the AL West, and who is either a free agent or arbitration eligible in 2016 or 2017, and the list below are the pitchers whose SCERA is under 3.80 (min. 20 IP). Some of these pitchers will be easier to acquire than others, but I believe these are pitchers that the Rangers should target to improve their bullpen. I included the players SCERA, ERA, and also their GB%. The reason I included their GB% is because the Rangers lead the league in double plays turned, so a pitcher with a high GB% might play even better than his SCERA suggests with the Rangers. I did not include any players who are on the disabled list.