Pending games as you know, shows the games you need to get done. You may find many games in finished cups or old league games and you wonder why they are listed there.
The reason is that normally we'd like you to get all those games done. There's a new feature in Cups which allows you to specify a percentage for people to join. Everybody has a played games percentage. I could start a cup and set things like only people with at least 80% done games must join. This helps the cup to run faster.
For that reason, people must be allowed to improve their done games percentage even though it has been some time. Now there are people who you can't reach at all. For this, you can request a moderator to mark those games as ignored for you.
Like members, clan have a pending games too. The number you see in your profile is actually your pending games + your clan pending games. So if you recruit a new member now, he/she will see your clan pending games too.
Pending games is still in its first steps and it turned out to be a little buggy on counts. It is on my to do list. Hope this topic clears some confusions.