This is a detailed breakdown of your player's performances in recent games, which should have a strong bearing on your selection policy.
The screen is awash with statistics which should not intimidate you as it's a key source of information on how well your player is performing. It's split into four sections for ease of use - Match Ratings, Summary, Detailed match ratings and Statistics.
Use the team drop-down to swap between club and international performances and the filter option to select the competitions you wish to see stats for - noting that players' stats are likely to be inflated against weaker opponents.

Match Rating
This graph is a useful at-a-glance representation of a player's performances over the last 20 matches. Note that a dip to zero means the player didn't appear in a game and can falsely depress your overall view of his performances. This graph is ideal for assessing the consistency of your player's performance as it stretches back over a lengthy period.

Summary
This overview provides a quick guide to a player's peaks and troughs of performance and also shows how many times they featured in games they could have played in. This fact alone is a useful tool in assessing a player, with many absences suggesting either that the player is not rated by his manager or not fit. If he is not rated this could open the door for an approach, but may also suggest he is not of the highest quality. You should check to see if his lack of appearances is down to a lack of fitness or injury proneness by examining his history and checking his Detailed match ratings.

Detailed Match Ratings
Corresponding with the player stats screen, these statistics break down a player's contribution to each game. As ever, abstract factors such as a player's attributes are no substitute for actual match ratings which show how a player has done in competitive action.
This breakdown will enable the thorough Football Manager to see precisely what an individual has, and hasn't, brought to the team. Consistently poor performances when a player is fit and well should not be tolerated. Go to the tactics screen and give another player a chance to shine.

When a player doesn't feature a brief explanation will appear in the relevant column - such as 'cup-tied' or 'unused substitute'. This information will help you to build up a picture of exactly how valued a player at a rival club is.

Statistics
This is the classic Football Manager view of a player's form as appears on their Profile page. These are the key statistics highlighting a player's performances over an entire season.
An at-a-glance set of stats that will help you to quickly asses the contribution of defenders, midfielders and strikers is the Tackle (Tck), Pass completion (Pass), and Shots on target (Sh Tar) data. A defender with a high tackling statistic, midfielder with good pass completion and striker with a good shots-on-target ratio can be seen to be doing their basic jobs effectively. Of course, your team selection and tactics should rest on a far more precise and complete analysis of a player's game, but these stats are a good starting point.