You can receive Tier Rewards and Defense Rewards for the Arena by entering the Arena between when one season ends and the season that follows ends.
Please keep in mind that the timing for when you can collect rewards may vary depending on the calculation process for season results. You can only collect Defense Rewards when your team has defended successfully.
If you have not participated in any given Arena season, your Tier will not decline, but you will also not receive Tier Rewards. In that case, if your team has defended successfully, you can only collect Defense Rewards.
Tier Rewards and 5-win streak rewards will not be sent to your Present List.