The Cubs sent Andrew Cashner and Kyung-Min Na to the Padres for Anthony Rizzo and and Zach Cates.
Cashner has 65 career MLB innings (basically all in relief), and has earned a .3 WAR in that time. His PE is .115, with an adjusted PE of .665. His FIP - is 117, but his SIERA is 3.94. He has a nice groundball ratio (1.52), but gave up 1.25 HR/9IP. He has a league average Pit/PA. A bigger sample size is his AA numbers, where he has pitched 97 innings and had a PE of -1.95, and gave up just .1 HR/9IP. His FIP was about 2.8, meaning he had a CWAR of about 1.26. This would be a negative WAR in the MLB according to our AA metric.
Na is a below average outfielder according to both fielding percentage and range factor. He has played 149 games in the minors, almost exclusively in different levels of A-ball (just 2 games in AA). There he has an OBP of .335 and OPS of just .619. This projects to a terrible .286 OBP and .453 OPS.
Rizzo has a -.7 WAR in 49 career MLB games. He has played 93 games in AAA, in the PCL. There he has a .404 OBP, 1.056 OPS, 2.2 PAPP, 2.7 PPG, for a great 6.44 Simple WAR. This projects to a 4.95 Simple WAR with an OBP of .358. Defensively, he isn't bad, with a 9.51 Range Factor and .989 Fielding Percentage at 1st base.
Cates has spent just one year in A ball, and had an even 0 PE as a starter, with an adjusted PE of -1.4. He has an okay walk rate, and gave up just .31 HR/9IP. His CWAR was 2.11, and if we assume that pitcher regression would be the same as hitter regression (that is the ratio of CWAR lost to Simple WAR lost is 1:1), he would have a -1.45 CWAR in the MLB. A different way might be to use the 22% regression that hitters see in their OPS from A ball-MLB and apply that to his FIP. This would project his FIP at 3.94, which would obviously lead to a positive WAR.
The Cubs get a first baseman that projects to be very good in the Majors, and a pitcher with a good strikeout rate and doesn't give up homers while the Padres get a player that can't play along with a reliever that doesn't project very well either and struggles with homers. This is a very lopsided trade.